Denial-of-service attack: Wikis

  
  

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DDoS Stacheldraht Attack diagram.
.A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users.^ In order to understand denial of service attacks, you should also understand distributed denial of service attacks.

^ Denial of service attacks ) electronic voting ( in electronic voting: I-voting ) zombie computers ( in zombie computer ) Other .
  • denial of service attack (DoS attack) (computer science) -- Britannica Online Encyclopedia 19 January 2010 18:018 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users.
  • Twitter is Under Attack! Denial of Service Cause of Downtime | But You're A Girl 19 January 2010 18:018 UTC butyoureagirl.com [Source type: General]
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial of Service attack on Amazon - AbhiSays.com 19 January 2010 18:018 UTC abhisays.com [Source type: General]
  • Twitter, Facebook hit by denial-of-service attacks_English_Xinhua 19 January 2010 18:018 UTC news.xinhuanet.com [Source type: News]
  • DDoS attack?what is it..-Buzz from India 12 September 2009 12:012 UTC in.cyberjadoo.com [Source type: General]

.Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the concerted efforts of a person or people to prevent an Internet site or service from functioning efficiently or at all, temporarily or indefinitely.^ Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC weblogs.asp.net [Source type: General]
  • Asp.net, Debugging, IIS : IIS 6.0 security in terms of DOS (Denial of Service) attack 19 January 2010 18:018 UTC blogs.msdn.com [Source type: General]

^ Denial of Service (DoS) attacks .
  • Denial of Service (DoS) attacks | Life. Web. and more. 19 January 2010 18:018 UTC www.marcelsmits.com [Source type: General]

^ Denial of Service attack targets .
  • Stop HTTP DoS attacks - Dos attack targets 19 January 2010 18:018 UTC www.applicure.com [Source type: FILTERED WITH BAYES]

.Perpetrators of DoS attacks typically target sites or services hosted on high-profile web servers such as banks, credit card payment gateways, and even root nameservers.^ Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC weblogs.asp.net [Source type: General]
  • Asp.net, Debugging, IIS : IIS 6.0 security in terms of DOS (Denial of Service) attack 19 January 2010 18:018 UTC blogs.msdn.com [Source type: General]

^ Denial of Service (DoS) attacks .
  • Denial of Service (DoS) attacks | Life. Web. and more. 19 January 2010 18:018 UTC www.marcelsmits.com [Source type: General]

^ Denial of Service attack targets .
  • Stop HTTP DoS attacks - Dos attack targets 19 January 2010 18:018 UTC www.applicure.com [Source type: FILTERED WITH BAYES]

.The term is generally used with regards to computer networks, but is not limited to this field, for example, it is also used in reference to CPU resource management.^ Computers and computer networks have limited capacities.

^ Some resources that are limited include bandwidth, database connections, disk storage, CPU, memory, threads, or application specific resources.
  • Application Denial of Service - OWASP 19 January 2010 18:018 UTC www.owasp.org [Source type: General]

^ Denial of service (DoS) usually refers to an attack that attempts to make a computer resource unavailable to its intended users by flooding a network or server with requests and data.
  • Denial of Service | Glossary | F5 Networks 22 September 2009 16:016 UTC www.f5.com [Source type: Academic]

[1]
.One common method of attack involves saturating the target (victim) machine with external communications requests, such that it cannot respond to legitimate traffic, or responds so slowly as to be rendered effectively unavailable.^ Commonly, attack involves simply saturating the target machine with external internet requests.
  • Denial of service denial | Science Codex 19 January 2010 18:018 UTC www.sciencecodex.com [Source type: FILTERED WITH BAYES]
  • Computer Network Denial Of Service Denial 19 January 2010 18:018 UTC www.sciencedaily.com [Source type: News]

^ One common method of attack involves saturating the target (victim) machine with external communications requests, such that it maple story mesos cannot respond to legitimate traffic, or responds so slowly as to be rendered effectively unavailable.
  • Recent DDoS Attack - Maple Story News - www.mesosmaple.com 19 November 2009 18:39 UTC www.mesosmaple.com [Source type: News]

^ This attack poisons the cache of the target machine.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

.In general terms, DoS attacks are implemented by either forcing the targeted computer(s) to reset, or consuming its resources so that it can no longer provide its intended service or obstructing the communication media between the intended users and the victim so that they can no longer communicate adequately.^ A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users.
  • Denial-of-Service 19 January 2010 18:018 UTC www.cknow.com [Source type: General]
  • Twitter is Under Attack! Denial of Service Cause of Downtime | But You're A Girl 19 January 2010 18:018 UTC butyoureagirl.com [Source type: General]
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • DDoS attack?what is it..-Buzz from India 12 September 2009 12:012 UTC in.cyberjadoo.com [Source type: General]
  • Recent DDoS Attack - Maple Story News - www.mesosmaple.com 19 November 2009 18:39 UTC www.mesosmaple.com [Source type: News]

^ DOS attack is a term which stands for denial of service attack.
  • DOS Attacks - Denial of Service Attacks 19 January 2010 18:018 UTC www.buzzle.com [Source type: News]

^ A denial-of-service attack ( DoS attack ) or distributed denial-of-service attack ( DDoS attack ) is an attempt to make a computer resource unavailable to its intended users.
  • Denial-of-service attack - IIX Hosting PANDUAN | Webhosting litespeed web server IIX+USA - Reseller Hosting Indonesia - Web Hosting Murah Terjangkau 11 September 2009 4:11 UTC www.id.rajaklik.com [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Denial-of-service attacks are considered violations of the IAB's Internet proper use policy, and also violate the acceptable use policies of virtually all Internet Service Providers.^ Denial of service attack articles .
  • Denial of service attack : DaveChaffey.com Internet Marketing 19 January 2010 18:018 UTC www.davechaffey.com [Source type: General]

^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ Update 7: It's a denial of service attack .
  • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) - washingtonpost.com 19 January 2010 18:018 UTC www.washingtonpost.com [Source type: News]

.They also commonly constitute violations of the laws of individual nations.^ DoS attacks commonly constitute violations of the laws of individual nations.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.prisonplanet.com [Source type: FILTERED WITH BAYES]

^ They also commonly constitute violations of the laws of individual nations .
  • Denial-of-service attack - IIX Hosting PANDUAN | Webhosting litespeed web server IIX+USA - Reseller Hosting Indonesia - Web Hosting Murah Terjangkau 11 September 2009 4:11 UTC www.id.rajaklik.com [Source type: FILTERED WITH BAYES]

^ They also commonly constitute violations of the laws of individual nations.
  • DDoS attack?what is it..-Buzz from India 12 September 2009 12:012 UTC in.cyberjadoo.com [Source type: General]
  • Recent DDoS Attack - Maple Story News - www.mesosmaple.com 19 November 2009 18:39 UTC www.mesosmaple.com [Source type: News]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[2]

Contents

Symptoms and Manifestations

The United States Computer Emergency Response Team defines symptoms of denial-of-service attacks to include:
  • Unusually slow network performance (opening files or accessing web sites)
  • Unavailability of a particular web site
  • Inability to access any web site
  • Dramatic increase in the number of spam emails received—(this type of DoS attack is considered an e-mail bomb)[3]
.Denial-of-service attacks can also lead to problems in the network 'branches' around the actual computer being attacked.^ Denial of service attack articles .
  • Denial of service attack : DaveChaffey.com Internet Marketing 19 January 2010 18:018 UTC www.davechaffey.com [Source type: General]

^ Denial of service attacks ) electronic voting ( in electronic voting: I-voting ) zombie computers ( in zombie computer ) Other .
  • denial of service attack (DoS attack) (computer science) -- Britannica Online Encyclopedia 19 January 2010 18:018 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Update 7: It's a denial of service attack .
  • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) - washingtonpost.com 19 January 2010 18:018 UTC www.washingtonpost.com [Source type: News]

.For example, the bandwidth of a router between the Internet and a LAN may be consumed by an attack, compromising not only the intended computer, but also the entire network.^ Computer Internet network security News .
  • Computer Internet network security News » Ddos 22 September 2009 16:10 UTC www.securiour.com [Source type: FILTERED WITH BAYES]

^ For example, the bandwidth of a router between the Internet and a LAN may be consumed by an attack, compromising not only the intended computer, but also the entire network.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack - IIX Hosting PANDUAN | Webhosting litespeed web server IIX+USA - Reseller Hosting Indonesia - Web Hosting Murah Terjangkau 11 September 2009 4:11 UTC www.id.rajaklik.com [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ This may indicate that your computer or your organization's network is being attacked.
  • US-CERT Cyber Security Tip ST04-015 -- Understanding Denial-of-Service Attacks 19 January 2010 18:018 UTC www.us-cert.gov [Source type: General]
  • Understanding Denial-of-Service Attacks | Attacks and threats 19 January 2010 18:018 UTC www.lancastrian-it.co.uk [Source type: General]

.If the attack is conducted on a sufficiently large scale, entire geographical regions of Internet connectivity can be compromised without the attacker's knowledge or intent by incorrectly configured or flimsy network infrastructure equipment.^ If the attack is conducted on a sufficiently large scale, entire geographical regions of Internet connectivity can be compromised without the attacker's knowledge or intent by incorrectly configured or flimsy network infrastructure equipment.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack - IIX Hosting PANDUAN | Webhosting litespeed web server IIX+USA - Reseller Hosting Indonesia - Web Hosting Murah Terjangkau 11 September 2009 4:11 UTC www.id.rajaklik.com [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ If the DoS is conducted in a sufficiently large scale, entire geographical swathes of Internet connectivity can also be compromised by incorrectly configured or flimsy network infrastructure equipment without the attacker's knowledge or intent.
  • DDOS 12 September 2009 12:012 UTC www.gss.co.uk [Source type: News]

^ Akamai confirmed that its servers were affected by "large-scale, international attack on internet infrastructure".
  • Google, Yahoo, Microsoft, hit by massive DDoS attack - CCTV Forums 19 November 2009 18:39 UTC www.cctvcore.co.uk [Source type: General]

Methods of attack

.A "denial-of-service" attack is characterized by an explicit attempt by attackers to prevent legitimate users of a service from using that service.^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ Update 7: It's a denial of service attack .
  • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) - washingtonpost.com 19 January 2010 18:018 UTC www.washingtonpost.com [Source type: News]

^ Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC weblogs.asp.net [Source type: General]
  • Asp.net, Debugging, IIS : IIS 6.0 security in terms of DOS (Denial of Service) attack 19 January 2010 18:018 UTC blogs.msdn.com [Source type: General]

.Attacks can be directed at any network device, including attacks on routing devices and web, electronic mail, or Domain Name System servers.^ The methods of attack range from attacks on electronic mail to attacks on routing devices and the web.
  • What is DoS Denial of Service attack? - EmailTalk.org Blog for IT Administrators : EmailTalk.org Blog 19 January 2010 18:018 UTC www.emailtalk.org [Source type: General]

^ The attacks were targeted at Network Solutions' Worldnic name servers .
  • Update: Two DNS servers hit by denial-of-service attacks 19 January 2010 18:018 UTC www.computerworld.com [Source type: News]

^ Name server checks its cache for the domain name.
  • JIBC 22 September 2009 16:10 UTC www.arraydev.com [Source type: FILTERED WITH BAYES]

.A DoS attack can be perpetrated in a number of ways.^ As this is a way to prevent from getting Attack by DoS again.
  • » One of a way on How to Prevent Denial Of Service Attack- DoS Attack - Blogs of Technology 19 January 2010 18:018 UTC xblog.x-sysonline.com [Source type: FILTERED WITH BAYES]

^ DoS/DDoS attacks can manifest in a number of ways.
  • Denial Of Service Attack | FireBlog | FireHost 19 January 2010 18:018 UTC www.fireblog.com [Source type: General]

^ A DoS attack can be perpetrated in a number of ways.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Cyber attackers (distributed denial of service (DDoS) target South Korea & US Governments websites: N. Korea believed behind | CEOWORLD Magazine 22 September 2009 16:10 UTC ceoworld.biz [Source type: News]
  • Denial-of-service attack - IIX Hosting PANDUAN | Webhosting litespeed web server IIX+USA - Reseller Hosting Indonesia - Web Hosting Murah Terjangkau 11 September 2009 4:11 UTC www.id.rajaklik.com [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

The five basic types of attack are:
  1. Consumption of computational resources, such as bandwidth, disk space, or processor time
  2. Disruption of configuration information, such as routing information.
  3. Disruption of state information, such as unsolicited resetting of TCP sessions.
  4. Disruption of physical network components.
  5. Obstructing the communication media between the intended users and the victim so that they can no longer communicate adequately.
A DoS attack may include execution of malware intended to:
  • Max out the processor's usage, preventing any work from occurring.
  • Trigger errors in the microcode of the machine.
  • Trigger errors in the sequencing of instructions, so as to force the computer into an unstable state or lock-up.
  • Exploit errors in the operating system, causing resource starvation and/or thrashing, i.e. to use up all available facilities so no real work can be accomplished.
  • Crash the operating system itself.

ICMP flood

.A smurf attack is one particular variant of a flooding DoS attack on the public Internet.^ The attack itself is a SYN Flooding or a Smurf Attack.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ Smurf is a new kind of DoS attack.
  • Denial of Service Attacks 19 January 2010 18:018 UTC www.cs.utexas.edu [Source type: FILTERED WITH BAYES]

^ A smurf attack is one particular variant of a flooding DoS attack on the public Internet.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.It relies on misconfigured network devices that allow packets to be sent to all computer hosts on a particular network via the broadcast address of the network, rather than a specific machine.^ This causes all the computers to respond to a different computer than actually sent the packet.
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]
  • The World Wide Web Security FAQ - Securing against Denial of Service attacks 19 January 2010 18:018 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

^ This is any network that allows such packets in.
  • Distributed Denial of Service Attacks 12 September 2009 12:012 UTC www.linuxsecurity.com [Source type: FILTERED WITH BAYES]

^ The Packets will be sent to a Broadcast address this will say that the all the computers on the network will get the ICMP Packet.
  • Denial Of Service Attacks: 19 January 2010 18:018 UTC www.go4expert.com [Source type: General]

.The network then serves as a smurf amplifier.^ The network then serves as a smurf amplifier.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ And a third defensive measure prevents you from being used to mount the smurf attacks that are part of this pattern of DDoS. Smurf attacks send packets to a ``smurf amplifier'' network.
  • Distributed Denial of Service Attacks 12 September 2009 12:012 UTC www.linuxsecurity.com [Source type: FILTERED WITH BAYES]

^ Smurfing": Amplified Network-based Denial of Service Attack is a white paper that discuses Smurfing.
  • Network Denial of Service Attacks. Can you hack it? | WebProNews 19 January 2010 18:018 UTC www.webpronews.com [Source type: General]

.In such an attack, the perpetrators will send large numbers of IP packets with the source address faked to appear to be the address of the victim.^ RFC2267 filtering is in place by attempting to send a packet with the source address of 3.3.3.3.
  • http://www.spirit.com/Network/net0100.html 22 September 2009 16:10 UTC www.spirit.com [Source type: FILTERED WITH BAYES]

^ The problem with DoS/DDoS attacks is that packets come from a large number of sources and IP address spoofing masks those sources.
  • Distributed Denial-Of-Service 19 January 2010 18:018 UTC www.garykessler.net [Source type: FILTERED WITH BAYES]

^ N]] Add IP addresses to list of attack victims.
  • SANS: Intrusion Detection FAQ: The "stacheldraht" Distributed Denial of Service Attack Tool 22 September 2009 16:10 UTC www.sans.org [Source type: FILTERED WITH BAYES]
  • dod1.htm: denial of service attack tools 11 September 2009 4:11 UTC www.crazyboy.com [Source type: Reference]

.The network's bandwidth is quickly used up, preventing legitimate packets from getting through to their destination.^ The network's bandwidth is quickly used up, preventing legitimate packets from getting through to their destination.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Filtering out all SYN/ACK packets having the destination IP of the targeted machine, by the ISP, will prevent the reflection data from flooding the targeted network’s bandwidth.
  • Distributed Reflection Denial of Service: A Bandwidth Attack : Palisade 19 January 2010 18:018 UTC palisade.plynt.com [Source type: FILTERED WITH BAYES]

^ A remote system is overwhelmed by a continuous flood of traffic designed to consume resources at the targeted server (CPU cycles and memory) and/or in the network (bandwidth and packet buffers).
  • DDoS Resources 19 January 2010 18:018 UTC anml.iu.edu [Source type: FILTERED WITH BAYES]

[4] .To combat Denial of Service attacks on the Internet, services like the Smurf Amplifier Registry have given network service providers the ability to identify misconfigured networks and to take appropriate action such as filtering.^ Denial of service attack articles .
  • Denial of service attack : DaveChaffey.com Internet Marketing 19 January 2010 18:018 UTC www.davechaffey.com [Source type: General]

^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ Update 7: It's a denial of service attack .
  • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) - washingtonpost.com 19 January 2010 18:018 UTC www.washingtonpost.com [Source type: News]

.Ping flood is based on sending the victim an overwhelming number of ping packets, usually using the "ping" command from unix like hosts (the -t flag on Windows systems has a far less malignant function).^ However, in PMP, any host can use the higher class to send any number of packets to any other host.
  • Protecting Electronic Commerce From DistributedDenial-of-Service Attacks 19 January 2010 18:018 UTC www2002.org [Source type: FILTERED WITH BAYES]

^ That is the attacker host will send a flood of syn packet but will not respond with an ACK packet.
  • Introduction to Denial of Service 22 September 2009 16:016 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

^ A Smurf attack is when an attacker will send ICMP based ping packet to a host.
  • Network Denial of Service Attacks. Can you hack it? | WebProNews 19 January 2010 18:018 UTC www.webpronews.com [Source type: General]

.It is very simple to launch, the primary requirement being access to greater bandwidth than the victim.^ It is very simple to launch, the primary requirement being access to greater bandwidth than the victim.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ In this type of attack the primary goal is to prevent the victim's machine of fulfilling its required job.
  • Denial ofService attacks - DoS, DDoS (SYN flood, email bombing, icmp attacks) 19 January 2010 18:018 UTC www.surasoft.com [Source type: FILTERED WITH BAYES]

^ It is very simple for anyone to launch an attack because denial-of-service tools can easily be procured from the Net.

.SYN flood sends a flood of TCP/SYN packets, often with a forged sender address.^ That is the attacker host will send a flood of syn packet but will not respond with an ACK packet.
  • Introduction to Denial of Service 22 September 2009 16:016 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

^ ICMP Error sending syn packet.
  • SANS: Intrusion Detection FAQ: The "stacheldraht" Distributed Denial of Service Attack Tool 22 September 2009 16:10 UTC www.sans.org [Source type: FILTERED WITH BAYES]
  • dod1.htm: denial of service attack tools 11 September 2009 4:11 UTC www.crazyboy.com [Source type: Reference]

^ The SYN flood works by sending SYN packets from false IP addresses (IP spoofing).
  • Stop Denial of Service attacks - Online Training and Tutorials 19 January 2010 18:018 UTC www.tutorial5.com [Source type: FILTERED WITH BAYES]

.Each of these packets is handled like a connection request, causing the server to spawn a half-open connection, by sending back a TCP/SYN-ACK packet, and waiting for a packet in response from the sender address.^ The server will sent he SYN ACK but it will not get a response.
  • Distributed denial of service attack inhibitor helps stop Windows servers from falling prey to TCPIP distributed denial of service attacks (D-DoS) when SYN-ACKs or SYN floods are mis-sent to spoofed IP addresses. 19 January 2010 18:018 UTC www.sigmasolutions.com.au [Source type: FILTERED WITH BAYES]

^ A connection is considered to be half open after the server has sent the SYN-ACK (in response to a SYN) but before the ACK is received.
  • Distributed Denial Of Service attack and registry settings to change in Windows server to lessen effect of SYN floods, SYN-ACK and DoS attacks 19 January 2010 18:018 UTC www.sigmasolutions.com.au [Source type: FILTERED WITH BAYES]

^ Client sends request to name server 2.
  • JIBC 22 September 2009 16:10 UTC www.arraydev.com [Source type: FILTERED WITH BAYES]

.However, because the sender address is forged, the response never comes.^ However, because the sender address is forged, the response never comes.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ There is no easy way to trace the originator of the attack because the IP address of the source is forged.
  • Defining Strategies to Protect Against TCP SYN Denial of Service Attacks - Cisco Systems 19 January 2010 18:018 UTC www.cisco.com [Source type: Reference]

^ SImilarly, a SYN flood sends many TCP/SYN packets with a forged sender address.
  • Denial-of-Service 19 January 2010 18:018 UTC www.cknow.com [Source type: General]

.These half-open connections saturate the number of available connections the server is able to make, keeping it from responding to legitimate requests until after the attack ends.^ If an attack is detected, the server selectively accepts connection requests by responding to each request with a puzzle.
  • Distributed Denial-Of-Service 19 January 2010 18:018 UTC www.garykessler.net [Source type: FILTERED WITH BAYES]

^ As a consequence of this attack, legitimate connections are denied.
  • Demystifying Denial-Of-Service attacks, part one 19 January 2010 18:018 UTC www.securityfocus.com [Source type: FILTERED WITH BAYES]

^ This is what we mean by half-open connection.
  • http://www.ufsdump.org/papers/uuasc-november-ddos.html 19 January 2010 18:018 UTC www.ufsdump.org [Source type: FILTERED WITH BAYES]

Teardrop Attacks

.A Teardrop attack involves sending mangled IP fragments with overlapping, over-sized payloads to the target machine.^ A Teardrop attack involves sending mangled IP fragments with overlapping, over-sized payloads to the target machine.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]

^ A Teardrop attack involves sending mangled IP fragments with overlapping, over-sized, payloads to the target machine.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Teardrop is an attack exploiting a weakness in the reassembly of IP packet fragments.
  • Denial of Service Attacks 19 January 2010 18:018 UTC www.cs.utexas.edu [Source type: FILTERED WITH BAYES]

.This can crash various operating systems due to a bug in their TCP/IP fragmentation re-assembly code.^ Crash the operating system itself.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Cyber attackers (distributed denial of service (DDoS) target South Korea & US Governments websites: N. Korea believed behind | CEOWORLD Magazine 22 September 2009 16:10 UTC ceoworld.biz [Source type: News]
  • Denial-of-service attack - IIX Hosting PANDUAN | Webhosting litespeed web server IIX+USA - Reseller Hosting Indonesia - Web Hosting Murah Terjangkau 11 September 2009 4:11 UTC www.id.rajaklik.com [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Some implementations of the TCP/IP IP fragmentation re-assembly code do not properly handle overlapping IP fragments.
  • CERT Advisory CA-1997-28 IP Denial-of-Service Attacks 11 September 2009 4:11 UTC www.cert.org [Source type: FILTERED WITH BAYES]

^ This can crash various operating systems due to a bug in their TCP/IP fragmentation re-assembly code.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[5] .Windows 3.1x, Windows 95 and Windows NT operating systems, as well as versions of Linux prior to versions 2.0.32 and 2.1.63 are vulnerable to this attack.^ Only Windows 3.11, 95 and Linux prior to 2.0.32 were vulnerable to this kind of attack.
  • Stop Denial of Service attacks - Online Training and Tutorials 19 January 2010 18:018 UTC www.tutorial5.com [Source type: FILTERED WITH BAYES]

^ Windows 3.1x, Windows 95 and Windows NT operating systems, as well as versions of Linux prior to versions 2.0.32 and 2.1.63 are vulnerable to this attack.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]

^ Operating systems such as Windows NT, Windows 95, and even Linux versions prior to version 2.1.63 are vulnerable to the teardrop attack.
  • How to Prevent Denial of Service Attacks : Learn-Networking.com 19 January 2010 18:018 UTC learn-networking.com [Source type: General]

Peer-to-peer attacks

.Attackers have found a way to exploit a number of bugs in peer-to-peer servers to initiate DDoS attacks.^ DDOS ) attacks made through its servers.
  • Article: Serious attack on Internet root servers. (Hacking).(Octber 21st, 2002, concerted distributed denial-of-service attack) - Information Systems Auditor | HighBeam Research - FREE trial 19 January 2010 18:018 UTC www.highbeam.com [Source type: Academic]

^ These attacks rely on bugs in peer-to-peer server software.
  • Denial-of-Service 19 January 2010 18:018 UTC www.cknow.com [Source type: General]

^ Massive DDoS Attack on its way?
  • DDoSInfo – Information about DDoS and Denial of Service Attacks 19 January 2010 18:018 UTC www.ddosinfo.com [Source type: General]

.The most aggressive of these peer-to-peer-DDoS attacks exploits DC++.^ The most aggressive of these peer-to-peer-DDoS attacks exploits DC++.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The attacks of several prominent Web sites during the week of February 6-12, 2000 used these Distributed Denial of Service (DDOS) attack tools.
  • DDOS Attacks 19 January 2010 18:018 UTC www.jmu.edu [Source type: FILTERED WITH BAYES]

^ For most hacks to work on websites, they consist of SQL injection or JavaScript injection attacks, these can only exist if you have forums or a search function.

.Peer-to-peer attacks are different from regular botnet-based attacks.^ Peer-to-peer attacks are different from regular botnet-based attacks.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The Attack Blocker does not have any settings for sanitizing packets, but does have a setting to specify a host that is treated differently than its peers in terms of reputation calculation.
  • Attack Blocker - UntangleWiki 19 January 2010 18:018 UTC wiki.untangle.com [Source type: FILTERED WITH BAYES]

.With peer-to-peer there is no botnet and the attacker does not have to communicate with the clients it subverts.^ There has been no live communication.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.prisonplanet.com [Source type: FILTERED WITH BAYES]

^ With peer-to-peer there is no botnet and the attacker does not have to communicate with the clients it subverts.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ From there, the attacker uses the master system to seek out and communicate with other machines, finding their vulnerabilities and enslaving them as well.

.Instead, the attacker acts as a 'puppet master,' instructing clients of large peer-to-peer file sharing hubs to disconnect from their peer-to-peer network and to connect to the victim’s website instead.^ Instead, the attacker acts as a 'puppet master,' instructing clients of large peer-to-peer file sharing hubs to disconnect from their peer-to-peer network and to connect to the victim’s website instead.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ This requires the attacker to have a faster network connection than the victim.
  • Denial of Service (DoS) Attacks-Top Bits 19 January 2010 18:018 UTC www.tech-faq.com [Source type: FILTERED WITH BAYES]

^ One of the worst causes clients of file-sharing hubs to disconnect and then reconnect to the victim's site.
  • Denial-of-Service 19 January 2010 18:018 UTC www.cknow.com [Source type: General]

.As a result, several thousand computers may aggressively try to connect to a target website.^ As a result, several thousand computers may aggressively try to connect to a target website.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The attack was launched by several thousand computers that had been commandeered and directed to overload SCO's site with multiple, repeated requests to cripple the company's online presence, according to SCO. .
  • Mac News: Security: SCO Hit with Another Denial-of-Service Attack 19 January 2010 18:018 UTC www.macnewsworld.com [Source type: News]

^ Estimates vary, but some 40% of Internet-connected computers may be under the control of criminals who can easily use them for a variety of criminal pursuits.
  • Hacker attack takes down Twitter, Facebook, LiveJournal - USATODAY.com 19 January 2010 18:018 UTC www.usatoday.com [Source type: News]

.While a typical web server can handle a few hundred connections/sec before performance begins to degrade, most web servers fail almost instantly under five or six thousand connections/sec.^ Most web servers can handle several hundred concurrent users under normal use.
  • SWAT Top Ten: Denial of Service (DoS) 19 January 2010 18:018 UTC www.upenn.edu [Source type: FILTERED WITH BAYES]
  • Application Denial of Service - OWASP 19 January 2010 18:018 UTC www.owasp.org [Source type: General]

^ So that the request gets analyzed before web server handles it.
  • Preventing DDoS Attacks - The Community's Center for Security 22 September 2009 16:10 UTC www.linuxsecurity.com [Source type: General]

^ While a typical web server can handle a few hundred connections/sec before performance begins to degrade, most web servers fail almost instantly under five or six thousand connections/sec.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.With a moderately big peer-to-peer attack a site could potentially be hit with up to 750,000 connections in a short order.^ With a moderately big peer-to-peer attack a site could potentially be hit with up to 750,000 connections in a short order.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Given that it takes hundreds of networked computers to take down a major Internet site in a denial-of-service attack, these networks could do significant damage.
  • Crypto-Gram: April 15, 2003 11 September 2009 4:11 UTC www.schneier.com [Source type: FILTERED WITH BAYES]

^ Companies running with a bandwidth limit may have to pay up to get their site back online, and some attacks are so vicious hardware might need to be replaced.
  • Need to Know: Denial of Service | IT PRO 19 January 2010 18:018 UTC www.itpro.co.uk [Source type: General]

.The targeted web server will be plugged up by the incoming connections.^ The targeted web server will be plugged up by the incoming connections.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The web server allocates an amount of hardware resource for each incoming connection.
  • Denial-of-service Attack | Developer Oracles 19 January 2010 18:018 UTC devoracles.com [Source type: General]
  • Distributed Denial Of Service Attack | Developer Oracles 19 January 2010 18:018 UTC devoracles.com [Source type: General]

^ Typically the targets are high-profile web servers where the attack is aiming to cause the hosted web pages to be unavailable on the Internet.
  • Domain term for - Denial of Service Attack 19 January 2010 18:018 UTC www.domainhostingall.com [Source type: FILTERED WITH BAYES]

.While peer-to-peer attacks are easy to identify with signatures, the large number of IP addresses that need to be blocked (often over 250,000 during the course of a big attack) means that this type of attack can overwhelm mitigation defenses.^ Block undesired IP addresses.
  • Denial of Service (DoS) Attack | uCertify Articles 19 January 2010 18:018 UTC www.ucertify.com [Source type: FILTERED WITH BAYES]

^ While peer-to-peer attacks are easy to identify with signatures, the large number of IP addresses that need to be blocked (often over 250,000 during the course of a big attack) means that this type of attack can overwhelm mitigation defenses.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ On the other hand, prevention of the attack or the response and traceback of perpetrators is extremely difficult due to a large number of attacking machines, the use of source-address spoofing and the similarity between legitimate and attack traffic.
  • CiteSeerX — D-WARD: Source-End Defense Against Distributed Denial-of-Service Attacks 22 September 2009 16:10 UTC citeseerx.ist.psu.edu [Source type: Academic]

.Even if a mitigation device can keep blocking IP addresses, there are other problems to consider.^ Block undesired IP addresses.
  • Denial of Service (DoS) Attack | uCertify Articles 19 January 2010 18:018 UTC www.ucertify.com [Source type: FILTERED WITH BAYES]

^ Even if a mitigation device can keep blocking IP addresses, there are other problems to consider.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ By looking at the unique IP address of the attempted hacker, a Sys Admin can block incoming traffic from that IP or group of related IP addresses.
  • Twitter, Facebook, Denial of Service Attacks | Bare Feet Studios 19 January 2010 18:018 UTC www.barefeetstudios.com [Source type: General]

.For instance, there is a brief moment where the connection is opened on the server side before the signature itself comes through.^ For instance, there is a brief moment where the connection is opened on the server side before the signature itself comes through.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Packets arriving at your firewall may be blocked there, but they may easily have already overwhelmed the incoming side of your Internet connection.
  • http://www.spirit.com/Network/net0100.html 22 September 2009 16:10 UTC www.spirit.com [Source type: FILTERED WITH BAYES]

^ On the technical side, we don't allow connections from open wingate servers, which helps a little.
  • Advogato: Open Projects Net: Denial of Service Attacks 19 January 2010 18:018 UTC www.advogato.org [Source type: General]

.Only once the connection is opened to the server can the identifying signature be sent and detected, and the connection torn down.^ Only once the connection is opened to the server can the identifying signature be sent and detected, and the connection torn down.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ These errors are down to the SQL Server being so busy that it cannot open new TCP/IP ports.

^ OTA setting can also be sent such that connection settings can be altered to divert all MMS to the attacker's server.
  • Schneier on Security: SMS Denial-of-Service Attack 19 January 2010 18:018 UTC www.schneier.com [Source type: FILTERED WITH BAYES]

.Even tearing down connections takes server resources and can harm the server.^ Even tearing down connections takes server resources and can harm the server.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The server/device is not able to complete the connection and as a result the server ends up using the majority of its network resources trying to acknowledge each SYN. .
  • Denial Of Service Attack | WebProNews 19 January 2010 18:018 UTC www.webpronews.com [Source type: General]

^ Apparently, the attack took advantage of a weakness in the player logging features in the Arena mode and could take down an entire server / server cluster.
  • Denial of Service Attack against World of Warcraft - Hotfixed - PlayNoEvil - Game Security, IT Security, and Secure Game Design Services 19 January 2010 18:018 UTC playnoevil.com [Source type: General]

.This method of attack can be prevented by specifying in the p2p protocol which ports are allowed or not.^ This method of attack can be prevented by specifying in the p2p protocol which ports are allowed or not.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ There are also SW on the market that can detect such attacks by PROTOCOL, thus you can limit and prevent attacks, but also Network Ops needs to understand what a attack is...and take action.
  • Denial-of-service-attack worries dominate Cisco patching -- Government Computer News 19 January 2010 18:018 UTC gcn.com [Source type: News]
  • Denial-of-service-attack worries dominate Cisco patching -- Government Computer News 19 January 2010 18:018 UTC gcn.com [Source type: News]

^ The introduction of the domain name system (DNS) successfully prevented this kind of attack and allowed the Internet to scale up to its current size of millions of hosts.
  • The Ignored Threat: Unintentional Denial of Service Attacks 19 January 2010 18:018 UTC blog.tekelec.com [Source type: FILTERED WITH BAYES]

.If port 80 is not allowed, the possibilities for attack on websites can be very limited.^ If port 80 is not allowed, the possibilities for attack on websites can be very limited.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ For example if the attack is employing ICMP packets or TCP SYN packets you could configure the system to specificly limit the bandwidth those types of packets will be allowed to consume.
  • ServerSignature.com - Subject: DDOS Attack Mitigation 19 November 2009 18:39 UTC www.serversignature.com [Source type: FILTERED WITH BAYES]

^ Though it is very little you can do to protect your website from such an attack, a proactive web host can make all the difference.

Permanent denial-of-service attacks

.A permanent denial-of-service (PDoS), also known loosely as phlashing,[6] is an attack that damages a system so badly that it requires replacement or reinstallation of hardware.^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ Denial of service attacks .
  • Denial of service attacks - ServerBeach Forums 19 January 2010 18:018 UTC forums.serverbeach.com [Source type: General]

^ Such an attack is known as a Distributed Denial-of-Service (DDoS) attack.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

[7] .Unlike the distributed denial-of-service attack, a PDoS attack exploits security flaws which allow remote administration on the management interfaces of the victim's hardware, such as routers, printers, or other networking hardware.^ Denial of service attacks ) electronic voting ( in electronic voting: I-voting ) zombie computers ( in zombie computer ) Other .
  • denial of service attack (DoS attack) (computer science) -- Britannica Online Encyclopedia 19 January 2010 18:018 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ Such an attack is known as a Distributed Denial-of-Service (DDoS) attack.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

.The attacker uses these vulnerabilities to replace a device's firmware with a modified, corrupt, or defective firmware image—a process which when done legitimately is known as flashing. This therefore "bricks" the device, rendering it unusable for its original purpose until it can be repaired or replaced.^ These flaws leave the door open for an attacker to remotely 'update' the device firmware to a modified, corrupt or defective firmware image, therefore "bricking" the device and making it permanently unusable for its original purpose.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ From there, the attacker uses the master system to seek out and communicate with other machines, finding their vulnerabilities and enslaving them as well.

^ If the attackers shut off the original master hosts that are used in the attacks and assign false IP addresses to another set of attack hosts, the problem will continue.
  • CNN - The denial-of-service aftermath - February 14, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

.The PDoS is a pure hardware targeted attack which can be much faster and requires fewer resources than using a botnet in a DDoS attack.^ The PDoS is a pure hardware targeted attack which can be much faster and requires fewer resources than using a botnet in a DDoS attack.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ I hope this article on DDoS attacks was useful...
  • ddos attacks - FIND out more HERE in this article! 12 September 2009 12:012 UTC www.updatexp.com [Source type: General]

^ However, by using an extremely resilient stateful packet filter that will inexpensively drop any unwanted packets, surviving a DoS attack becomes much easier.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Because of these features, and the potential and high probability of security exploits on Network Enabled Embedded Devices (NEEDs), this technique has come to the attention of numerous hacker communities.^ Because of these features, and the potential and high probability of security exploits on Network Enabled Embedded Devices (NEEDs), this technique has come to the attention of numerous hacker communities.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]

^ Because of these features, and the potential and high probability of security exploits on Network Enabled Embedded Devices (NEEDs), this technique has come to the attention of numerous hacker communities such as Hack a Day .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The network exploit techniques vary.
  • Barbarians at the Gate: An Introduction to Distributed Denial of Service Attacks 22 September 2009 16:10 UTC online.securityfocus.com [Source type: FILTERED WITH BAYES]

.PhlashDance is a tool created by Rich Smith[8] (an employee of Hewlett-Packard's Systems Security Lab) used to detect and demonstrate PDoS vulnerabilities at the 2008 EUSecWest Applied Security Conference in London.^ Use the operating system's security measures .
  • Distributed Denial-of-Service Attacks and You 19 January 2010 18:018 UTC technet.microsoft.com [Source type: General]

^ Use intrusion detection tools.
  • Preventing DDoS Attacks - The Community's Center for Security 22 September 2009 16:10 UTC www.linuxsecurity.com [Source type: General]

^ PhlashDance is a tool created by Rich Smith (an employee of Hewlett-Packard's Systems Security Lab) used to detect and demonstrate PDoS vulnerabilities at the 2008 EUSecWest Applied Security Conference in London.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[8]

Application level floods

.On IRC, IRC floods are a common electronic warfare weapon.^ On IRC, IRC floods are a common electronic warfare weapon.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Various DoS-causing exploits such as buffer overflow can cause server-running software to get confused and fill the disk space or consume all available memory or CPU time.^ Various DoS-causing exploits such as buffer overflow can cause server-running software to get confused and fill the disk space or consume all available memory or CPU time.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The disk space available to the application.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ Denial-of-service (DOS) attacks take various forms but often involve a company's servers being flooded with data in an effort to disable them.
  • BBC NEWS | Technology | Hackers hit Twitter and Facebook 19 January 2010 18:018 UTC news.bbc.co.uk [Source type: News]

.Other kinds of DoS rely primarily on brute force, flooding the target with an overwhelming flux of packets, oversaturating its connection bandwidth or depleting the target's system resources.^ Other kinds of DoS rely primarily on brute force, flooding the target with an overwhelming flux of packets, oversaturating its connection bandwidth or depleting the target's system resources.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ These packets are designed to disable or overwhelm the target system, often forcing a reboot.
  • Distributed Denial of Service Attacks 19 January 2010 18:018 UTC chinese-school.netfirms.com [Source type: FILTERED WITH BAYES]
  • Distributed Denial of Service Attacks 22 September 2009 16:10 UTC technet.microsoft.com [Source type: FILTERED WITH BAYES]

^ According to the advisories, attackers could down a Cisco router or switch via a DOS attack by flooding them with H.323 multimedia protocol-based packets , with Network Time Protocol packets , with Session Initiation Protocol packets, or packets carrying requests in a number of other protocols.
  • Denial-of-service-attack worries dominate Cisco patching -- Government Computer News 19 January 2010 18:018 UTC gcn.com [Source type: News]
  • Denial-of-service-attack worries dominate Cisco patching -- Government Computer News 19 January 2010 18:018 UTC gcn.com [Source type: News]

.Bandwidth-saturating floods rely on the attacker having higher bandwidth available than the victim; a common way of achieving this today is via Distributed Denial of Service, employing a botnet.^ Twitter victim of denial-of-service attack .
  • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

^ These are secondary victims (of denial of service).
  • dod1.htm: denial of service attack tools 11 September 2009 4:11 UTC www.crazyboy.com [Source type: Reference]

^ For the ultimate victim of distributed denial-of-service attacks .
  • CERT Advisory CA-1999-17 Denial-of-Service Tools 22 September 2009 16:016 UTC www.cert.org [Source type: Reference]

.Other floods may use specific packet types or connection requests to saturate finite resources by, for example, occupying the maximum number of open connections or filling the victim's disk space with logs.^ SYN floods (also known as resource starvation attacks) may also be used.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Other floods may use specific packet types or connection requests to saturate finite resources by, for example, occupying the maximum number of open connections or filling the victim's disk space with logs.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ By flooding a target server with connection requests, the finite resources allocated to a specific service can be overwhelmed.
  • Denial of Service Attacks: A Clear and Present Danger - Industry Trend or Event | Telecommunications | Find Articles at BNET 19 January 2010 18:018 UTC findarticles.com [Source type: News]

.A "banana attack" is another particular type of DoS. It involves redirecting outgoing messages from the client back onto the client, preventing outside access, as well as flooding the client with the sent packets.^ A "banana attack" is another particular type of DoS. It involves redirecting outgoing messages from the client back onto the client, preventing outside access, as well as flooding the client with the sent packets.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Figure 5: Packets sent by each of the 4 client nodes during the deauthentication attack.
  • 802.11 Denial-of-Service Attacks: Real Vulnerabilities and Practical Solutions 19 January 2010 18:018 UTC www.sysnet.ucsd.edu [Source type: FILTERED WITH BAYES]

^ A DDOS attack is a type of DOS attack.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]

.An attacker with access to a victim's computer may slow it until it is unusable or crash it by using a fork bomb.^ So the computer to the victim will even crash or hang.
  • Denial Of Service Attacks: 19 January 2010 18:018 UTC www.go4expert.com [Source type: General]

^ An attacker with access to a victim's computer may slow it until it is unusable or crash it by using a fork bomb.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Attackers often use overflow exploit as a mechanism to establish themselves as authorized users with access to resources that are entrusted to a few select individuals within an IT organization.
  • Denial of Service Attacks: A Clear and Present Danger - Industry Trend or Event | Telecommunications | Find Articles at BNET 19 January 2010 18:018 UTC findarticles.com [Source type: News]

Nuke

.A Nuke is an old denial-of-service attack against computer networks consisting of fragmented or otherwise invalid ICMP packets sent to the target, achieved by using a modified ping utility to repeatedly send this corrupt data, thus slowing down the affected computer until it comes to a complete stop.^ Denial of service attacks ) electronic voting ( in electronic voting: I-voting ) zombie computers ( in zombie computer ) Other .
  • denial of service attack (DoS attack) (computer science) -- Britannica Online Encyclopedia 19 January 2010 18:018 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ Using this technique, an attacker sends multiple SYN packets to the target computer.
  • Denial of Service (DoS) Attack | uCertify Articles 19 January 2010 18:018 UTC www.ucertify.com [Source type: FILTERED WITH BAYES]

.A specific example of a nuke attack that gained some prominence is the WinNuke, which exploited the vulnerability in the NetBIOS handler in Windows 95.^ Applications attacks rely on specific vulnerabilities found in some applications.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ A specific example of a nuke attack that gained some prominence is the WinNuke, which exploited the vulnerability in the NetBIOS handler in Windows 95.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ But, newer operating systems are sometimes vulnerable (e.g., at this writing, hackers are still finding some holes in Windows XP and NT that, in theory, could be exploited by an ActiveX control or, perhaps, a Netscape plug-in; as found, these holes are being plugged).
  • DoS - Denial-of-Service 19 January 2010 18:018 UTC www.cknow.com [Source type: FILTERED WITH BAYES]

.A string of out-of-band data was sent to TCP port 139 of the victim's machine, causing it to lock up and display a Blue Screen of Death (BSOD).^ This causes the connection queues and memory buffer to fill up, thereby denying service to legitimate TCP users.
  • Hacking Tutorial: Denial of Service (DOS) Attacks 19 January 2010 18:018 UTC www.expertsforge.com [Source type: FILTERED WITH BAYES]

^ What DEVM does is that once you start APF with DEVM to 1, it will set a cron job to stop APF in 5 minutes so you don't end up locking yourself out.
  • Denial of service attacks - ServerBeach Forums 19 January 2010 18:018 UTC forums.serverbeach.com [Source type: General]

^ The alleged flaw could allow an attack that could cause the "Blue Screen of Death."
  • Denial Of Service Attack Resources | ZDNet 11 September 2009 4:11 UTC updates.zdnet.com [Source type: General]

Distributed attack

.A distributed denial of service attack (DDoS) occurs when multiple systems flood the bandwidth or resources of a targeted system, usually one or more web servers.^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ However, a distributed denial-of-service attack (DDoS) is an entirely different story.
  • DDOS 12 September 2009 12:012 UTC www.gss.co.uk [Source type: News]

^ Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC weblogs.asp.net [Source type: General]

.These systems are compromised by attackers using a variety of methods.^ These systems are compromised by attackers using a variety of methods.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ From there, the attacker uses the master system to seek out and communicate with other machines, finding their vulnerabilities and enslaving them as well.

^ By using a single command, the attacker can instruct those machines to initiate one of numerous attacks on specific systems.

.Malware can carry DDoS attack mechanisms; one of the better-known examples of this was MyDoom.^ The MyDoom virus is an example of building such a DDoS attack network.
  • What is a Distributed Denial of Service (DDoS) Attack and What Can I Do About It? 12 September 2009 12:012 UTC www.cert.org [Source type: General]

^ Malware can carry DDoS attack mechanisms; one of the more well known examples of this was MyDoom.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Malware can carry DDoS attack mechanisms; one of the better-known examples of this was MyDoom.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]

.Its DoS mechanism was triggered on a specific date and time.^ Its DoS mechanism was triggered on a specific date and time.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.This type of DDoS involved hardcoding the target IP address prior to release of the malware and no further interaction was necessary to launch the attack.^ In part, that's because there are so many types of DDoS attacks that can be launched.
  • ddos attacks - FIND out more HERE in this article! 12 September 2009 12:012 UTC www.updatexp.com [Source type: General]

^ This type of attack does not involve breaking into the target system.

^ This type of DDoS involved hardcoding the target IP address prior to release of the malware and no further interaction was necessary to launch the attack.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.A system may also be compromised with a trojan, allowing the attacker to download a zombie agent (or the trojan may contain one).^ A system may also be compromised with a trojan, allowing the attacker to download a zombie agent (or the trojan may contain one).
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]

^ Once the appropriate organizations have been identified, the victim must ask each of them one by one to either help clean up or shut down their compromised system.

^ Short for D istributed D enial o f S ervice , it is an attack where multiple compromised systems (which are usually infected with a Trojan ) are used to target a single system causing a Denial of Service (DoS) attack.
  • DDoS attack - Internetnews.com - Webopedia.com 19 November 2009 18:39 UTC inews.webopedia.com [Source type: General]

.Attackers can also break into systems using automated tools that exploit flaws in programs that listen for connections from remote hosts.^ Agents are compromised via the handlers by the attacker, using automated routines to exploit vulnerabilities in programs that accept remote connections running on the targeted remote hosts.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Attackers can also break into systems using automated tools that exploit flaws in programs that listen for connections from remote hosts.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ After connecting to the handler using the client program, the attacker is prompted for a password.
  • SANS: Intrusion Detection FAQ: The "stacheldraht" Distributed Denial of Service Attack Tool 22 September 2009 16:10 UTC www.sans.org [Source type: FILTERED WITH BAYES]

.This scenario primarily concerns systems acting as servers on the web.^ This scenario primarily concerns systems acting as servers on the web.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Many of the services offered by your operating system are not required by your web server, for example RPC-based services.
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]
  • The World Wide Web Security FAQ - Securing against Denial of Service attacks 19 January 2010 18:018 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

^ Todays web servers don't work as stand alone systems but need the support of a number of backend systems (like database- or file-servers) to fulfill their tasks.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

.Stacheldraht is a classic example of a DDoS tool.^ Stacheldraht is a classic example of a DDoS tool.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The NIPC has made available a tool called "find_ddos" that searches the filesystem for the Trinoo, TNF, TNF2K and Stacheldraht DDOS tools.
  • ServerSignature.com - Subject: DDOS Attack Mitigation 19 November 2009 18:39 UTC www.serversignature.com [Source type: FILTERED WITH BAYES]

^ Because the data traces included no known DoS attacks, the researchers added overlaid attack traffic provided by the Stacheldraht DDoS attack tool.
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

.It utilizes a layered structure where the attacker uses a client program to connect to handlers, which are compromised systems that issue commands to the zombie agents, which in turn facilitate the DDoS attack.^ These compromised systems are the initial victims of the DDoS attack.
  • Distributed Denial-Of-Service 19 January 2010 18:018 UTC www.garykessler.net [Source type: FILTERED WITH BAYES]

^ DdoS agents and controlled by the attacker .
  • http://www.ufsdump.org/papers/uuasc-november-ddos.html 19 January 2010 18:018 UTC www.ufsdump.org [Source type: FILTERED WITH BAYES]

^ These systems are compromised by attackers using a variety of methods.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Agents are compromised via the handlers by the attacker, using automated routines to exploit vulnerabilities in programs that accept remote connections running on the targeted remote hosts.^ Agents are compromised via the handlers by the attacker, using automated routines to exploit vulnerabilities in programs that accept remote connections running on the targeted remote hosts.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ DDoS handler and daemon programs, lists of vulnerable and previously compromised hosts, etc.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

^ An Agent is a compromised host that is running a special program.
  • Strategies to Protect Against Distributed Denial of Service (DDoS) Attacks - Cisco Systems 22 September 2009 16:10 UTC www.cisco.com [Source type: Reference]

.Each handler can control up to a thousand agents.^ Each handler is capable of controlling multiple agents.
  • Strategies to Protect Against Distributed Denial of Service (DDoS) Attacks - Cisco Systems 22 September 2009 16:10 UTC www.cisco.com [Source type: Reference]

^ Each handler can control many agents.
  • SANS: Intrusion Detection FAQ: The "stacheldraht" Distributed Denial of Service Attack Tool 22 September 2009 16:10 UTC www.sans.org [Source type: FILTERED WITH BAYES]

^ Each handler can control up to a thousand agents.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[9]
.These collections of systems compromisers are known as botnets.^ These collections of systems compromisers are known as botnets.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ These are primary victims (of system compromise.
  • SANS: Intrusion Detection FAQ: The "stacheldraht" Distributed Denial of Service Attack Tool 22 September 2009 16:10 UTC www.sans.org [Source type: FILTERED WITH BAYES]
  • dod1.htm: denial of service attack tools 11 September 2009 4:11 UTC www.crazyboy.com [Source type: Reference]

^ They will then use these computers, known as zombies, to overwhelm other systems.
  • Dealing With Distributed Denial of Service Attacks 19 January 2010 18:018 UTC webhosting.devshed.com [Source type: General]

.DDoS tools like stacheldraht still use classic DoS attack methods centered on IP spoofing and amplification like smurf attacks and fraggle attacks (these are also known as bandwidth consumption attacks).^ Until recently, the tools used to mitigate DDoS attacks were inadequate.
  • Distributed Denial of Service Attacks:Protect Your Site from this Growing Threat - AML & Anti Fraud - FST US | GDS Publishing 19 January 2010 18:018 UTC www.usfst.com [Source type: FILTERED WITH BAYES]

^ To describe and understand DDoS attacks, it is important to understand the terminology that is used to describe the attacks and the tools.
  • Distributed Denial-Of-Service 19 January 2010 18:018 UTC www.garykessler.net [Source type: FILTERED WITH BAYES]

^ This won't stop all DDoS attacks, but it will stop some of them like Smurfing.
  • ddos attacks - FIND out more HERE in this article! 12 September 2009 12:012 UTC www.updatexp.com [Source type: General]

.SYN floods (also known as resource starvation attacks) may also be used.^ The attack itself is a SYN Flooding or a Smurf Attack.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ Use syn flooding.
  • Introduction to Denial of Service 22 September 2009 16:016 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

^ Example: SYN Flood attacks .
  • Demystifying Denial-Of-Service attacks, part one 19 January 2010 18:018 UTC www.securityfocus.com [Source type: FILTERED WITH BAYES]

.Newer tools can use DNS servers for DoS purposes.^ Newer tools can use DNS servers for DoS purposes.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ (Denial of Service Attack) The best know DoS tools, used for setting up and launchin a DoS attack, that use this system are: trinoo, tfn, and stacheldradt.
  • CoolMacintosh.com: DOS Attack Report 19 January 2010 18:018 UTC www.coolmacintosh.com [Source type: General]

^ As servers go, DNS servers are not particularly vulnerable to DoS. So long as a DNS server has sufficient memory, a modern host can usually respond very rapidly to DNS requests for which it is authoritative.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

(see next section)
.Simple attacks such as SYN floods may appear with a wide range of source IP addresses, giving the appearance of a well distributed DDoS. These flood attacks do not require completion of the TCP three way handshake and attempt to exhaust the destination SYN queue or the server bandwidth.^ The attack itself is a SYN Flooding or a Smurf Attack.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ Such an attack is known as a Distributed Denial-of-Service (DDoS) attack.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ What is distributed DoS (DDoS) attack?
  • Denial of Service (DoS) and DDoS Attacks 19 January 2010 18:018 UTC www.topwebhosts.org [Source type: FILTERED WITH BAYES]

.Because the source IP addresses can be trivially spoofed, an attack could come from a limited set of sources, or may even originate from a single host.^ This will ensure that attackers can’t spoof their IP address.
  • How to Prevent Denial of Service Attacks : Learn-Networking.com 19 January 2010 18:018 UTC learn-networking.com [Source type: General]

^ First, it may be a spoofed IP address, and thus, a false lead.
  • How to Prevent Denial of Service Attacks : Learn-Networking.com 19 January 2010 18:018 UTC learn-networking.com [Source type: General]

^ List IP addresses of hosts being DoS attacked at the moment.
  • dod1.htm: denial of service attack tools 11 September 2009 4:11 UTC www.crazyboy.com [Source type: Reference]

Stack enhancements such as syn cookies may be effective mitigation against SYN queue flooding, however complete bandwidth exhaustion may require involvement
.Unlike MyDoom's DDoS mechanism, botnets can be turned against any IP address.^ Unlike MyDoom's DDoS mechanism, botnets can be turned against any IP address.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ If the target of the DDoS attack is a single machine, a simple IP address change can end the flood.
  • Page 4 - Dealing With Distributed Denial of Service Attacks 19 January 2010 18:018 UTC webhosting.devshed.com [Source type: General]

^ In practicality, this will not reduce the impact of DDoS tools that do not spoof their address or only spoof the last 8 bits of the IP address, making it appear to be originating from the local network that the agent resides on.
  • Analyzing Distributed Denial Of Service Tools: The Shaft Case 22 September 2009 16:10 UTC www.usenix.org [Source type: FILTERED WITH BAYES]

.Script kiddies use them to deny the availability of well known websites to legitimate users.^ Script kiddies use them to deny the availability of well known websites to legitimate users.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Test platforms such as Mu Dynamics' Service Analyzer are available to perform simulated denial-of-service attacks that can be used to evaluate defensive mechanisms such IPS, RBIPS, as well as the popular denial-of-service mitigation products from Arbor Networks.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ As a result, legitimate traffic will be ignored and the object's users will be denied access.
  • Barbarians at the Gate: An Introduction to Distributed Denial of Service Attacks 22 September 2009 16:10 UTC online.securityfocus.com [Source type: FILTERED WITH BAYES]

[2] .More sophisticated attackers use DDoS tools for the purposes of extortion — even against their business rivals.^ The attacks of several prominent Web sites during the week of February 6-12, 2000 used these Distributed Denial of Service (DDOS) attack tools.
  • DDOS Attacks 19 January 2010 18:018 UTC www.jmu.edu [Source type: FILTERED WITH BAYES]

^ A more sophisticated approach would be to re-direct traffic intended for the user to another machine (which is similar to a DOS /Middle Man attack hackers use).
  • Denial of service dos attacks articles - Techworld.com 19 January 2010 18:018 UTC search.techworld.com [Source type: General]

^ As described earlier, it is much more likely that some hosts inside a local network will be taken over by remote hackers for use as zombies in coordinated DDoS attacks.
  • Cs3 - The Reverse Firewall: Defeating DDoS 12 September 2009 12:012 UTC www.cs3-inc.com [Source type: FILTERED WITH BAYES]

[10]
.It is important to note the difference between a DDoS and DoS attack.^ A DDOS attack is a type of DOS attack.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]

^ It is important to note the difference between a DDoS and DoS attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Increasingly, such attacks come from multiple, physically and network-topologically separated locations - a variation dubbed "Distributed" DoS attacks or DDoS attacks -...
  • Denial Of Service Attack Resources | ZDNet 11 September 2009 4:11 UTC updates.zdnet.com [Source type: General]

.If an attacker mounts an attack from a single host it would be classified as a DoS attack.^ Is the attack against a single host, or multiple hosts?
  • Preventing Denial of Service Attacks - O'Reilly Media 19 January 2010 18:018 UTC onlamp.com [Source type: General]

^ If an attacker mounts a smurf attack from a single host it would be classified as a DoS attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ If the attackers shut off the original master hosts that are used in the attacks and assign false IP addresses to another set of attack hosts, the problem will continue.
  • CNN - The denial-of-service aftermath - February 14, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

.In fact, any attack against availability would be classed as a Denial of Service attack.^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ Denial of Service preludes to criminal attacks .
  • DNS attacks 19 January 2010 18:018 UTC www.witiger.com [Source type: News]

^ Update: we are defending against a denial-of-service attack.

.On the other hand, if an attacker uses a thousand systems to simultaneously launch smurf attacks against a remote host, this would be classified as a DDoS attack.^ Attackers can hijack comps from other side of a globe to use for attack.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]

^ On the other hand, if an attacker uses a thousand zombie systems to simultaneously launch smurf attacks against a remote host, this would be classified as a DDoS attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Is the attack against a single host, or multiple hosts?
  • Preventing Denial of Service Attacks - O'Reilly Media 19 January 2010 18:018 UTC onlamp.com [Source type: General]

.The major advantages to an attacker of using a distributed denial-of-service attack are that multiple machines can generate more attack traffic than one machine, multiple attack machines are harder to turn off than one attack machine, and that the behavior of each attack machine can be stealthier, making it harder to track down and shut down.^ Avoiding future denial-of-service attacks .
  • CNN.com - Technology - Avoiding future denial-of-service attacks - February 23, 2000 19 January 2010 18:018 UTC archives.cnn.com [Source type: News]

^ Such an attack is known as a Distributed Denial-of-Service (DDoS) attack.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ Introduction A Denial-of-Service (DoS) attack is an attack in which one or more machines target a victim and attempt to prevent the victim from doing useful work.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

.These attacker advantages cause challenges for defense mechanisms.^ These attacker advantages cause challenges for defense mechanisms.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Both of these mechanisms may be exploited by an attacker.
  • 802.11 Denial-of-Service Attacks: Real Vulnerabilities and Practical Solutions 19 January 2010 18:018 UTC www.sysnet.ucsd.edu [Source type: FILTERED WITH BAYES]

^ The goal of DoS L2 (possibly DDoS) attack is to cause a launching of a defense mechanism which blocks the network segment from which the attack originated.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]

.For example, merely purchasing more incoming bandwidth than the current volume of the attack might not help, because the attacker might be able to simply add more attack machines.^ For example, merely purchasing more incoming bandwidth than the current volume of the attack might not help, because the attacker might be able to simply add more attack machines.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ This attack is more a concept than a real attack.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ A new type of attack launched from a single machine with limited hardware resources and bandwidth can cripple many of the webservers on the Internet today.
  • denial of service - news tag - Softpedia 19 January 2010 18:018 UTC news.softpedia.com [Source type: News]

Reflected attack

.A distributed reflected denial of service attack (DRDoS) involves sending forged requests of some type to a very large number of computers that will reply to the requests.^ Denial of service attacks ) electronic voting ( in electronic voting: I-voting ) zombie computers ( in zombie computer ) Other .
  • denial of service attack (DoS attack) (computer science) -- Britannica Online Encyclopedia 19 January 2010 18:018 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Denial of service attacks .
  • Denial of service attacks - ServerBeach Forums 19 January 2010 18:018 UTC forums.serverbeach.com [Source type: General]

^ Such an attack is known as a Distributed Denial-of-Service (DDoS) attack.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

.Using Internet protocol spoofing, the source address is set to that of the targeted victim, which means all the replies will go to (and flood) the target.^ This filters out the most commonly used spoofed source address.
  • Denial Of Service Attacks Explained And Prevention - Forums 19 January 2010 18:018 UTC www.governmentsecurity.org [Source type: General]

^ All hosts reply to the target, flooding it.
  • Stop Denial of Service attacks - Online Training and Tutorials 19 January 2010 18:018 UTC www.tutorial5.com [Source type: FILTERED WITH BAYES]

^ The attacker spoofs the requests with the victim's address.
  • Protecting Electronic Commerce From DistributedDenial-of-Service Attacks 19 January 2010 18:018 UTC www2002.org [Source type: FILTERED WITH BAYES]

.ICMP Echo Request attacks (Smurf Attack) can be considered one form of reflected attack, as the flooding host(s) send Echo Requests to the broadcast addresses of mis-configured networks, thereby enticing many hosts to send Echo Reply packets to the victim.^ The attack itself is a SYN Flooding or a Smurf Attack.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ If a machine receives that packet, that machine will return an ICMP echo reply packet.
  • http://www.ufsdump.org/papers/uuasc-november-ddos.html 19 January 2010 18:018 UTC www.ufsdump.org [Source type: FILTERED WITH BAYES]

^ This attack uses UDP echo packets in the same was as the ICMP echo traffic.
  • Denial Of Service Attacks : DDOS Attack & Network Attack 19 January 2010 18:018 UTC www.streetdirectory.com [Source type: General]

.Some early DDoS programs implemented a distributed form of this attack.^ Some early DDoS programs implemented a distributed form of this attack.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ We'll also discuss Teardrop attacks, LAND attacks, Ping-of-death, and finally discuss some common Win32 worms that have been used to build botnets that perform broad DDoS attacks.
  • Demystifying Denial-Of-Service attacks, part one 19 January 2010 18:018 UTC www.securityfocus.com [Source type: FILTERED WITH BAYES]

^ If they're trying to build a botnet for DDOS [Distributed Denial Of Service attacks ] for example, they want machines with high bandwidth so they can overload servers.
  • Denial of service dos attacks articles - Techworld.com 19 January 2010 18:018 UTC search.techworld.com [Source type: General]

.Many services can be exploited to act as reflectors, some harder to block than others.^ Many services can be exploited to act as reflectors, some harder to block than others.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ DDoS attacks occur when many hosts act in a cooperative manner to perform a joint denial of service attack, increasing the potential for overrunning the network dramatically.
  • Spirent announces enhanced security testing to protect networks from attacks - denial of service attack module for its Avalanche/2200 system | EDP Weekly's IT Monitor | Find Articles at BNET 19 January 2010 18:018 UTC findarticles.com [Source type: News]

^ Service supplier Siemens was forced to block addresses and prevent the attack using other methods like changing the DNS settings.” .
  • BBC hit by a DDoS attack | Zero Day | ZDNet.com 19 November 2009 18:39 UTC blogs.zdnet.com [Source type: General]

[11] .DNS amplification attacks involve a new mechanism that increased the amplification effect, using a much larger list of DNS servers than seen earlier.^ Many of the routing attacks can also be used against DNS servers by targeting the routing for the server.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ DNS amplification attacks involve a new mechanism that increased the amplification effect, using a much larger list of DNS servers than seen earlier.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ A DDoS attack involves sending large amounts of data that renders Web servers unusable by obstructing communication between the intended server and the target.
  • Urgent-Massive DDOS Attack! 12 September 2009 12:012 UTC forums.comodo.com [Source type: General]

[12]

Degradation-of-service attacks

."Pulsing" zombies are compromised computers that are directed to launch intermittent and short-lived floodings of victim websites with the intent of merely slowing it rather than crashing it.^ "Pulsing" zombies are compromised computers that are directed to launch intermittent and short-lived floodings of victim websites with the intent of merely slowing it rather than crashing it.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]

^ In this case the victim computers are called zombies.
  • How to Prevent Denial of Service Attacks : Learn-Networking.com 19 January 2010 18:018 UTC learn-networking.com [Source type: General]

^ The website just gets flooded with pings which will eat up the allotted bandwidth of the system or server, eventually causing said system to crash.
  • Oooh Dramatic! Twitter Gets DDOSed 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

.This type of attack, referred to as "degradation-of-service" rather than "denial-of-service", can be more difficult to detect than regular zombie invasions and can disrupt and hamper connection to websites for prolonged periods of time, potentially causing more damage than concentrated floods.^ Denial of service attacks ) electronic voting ( in electronic voting: I-voting ) zombie computers ( in zombie computer ) Other .
  • denial of service attack (DoS attack) (computer science) -- Britannica Online Encyclopedia 19 January 2010 18:018 UTC www.britannica.com [Source type: FILTERED WITH BAYES]

^ Denial of service attacks .
  • Denial of service attacks - ServerBeach Forums 19 January 2010 18:018 UTC forums.serverbeach.com [Source type: General]

^ Denial of Service preludes to criminal attacks .
  • DNS attacks 19 January 2010 18:018 UTC www.witiger.com [Source type: News]

[13][14] .Exposure of degradation-of-service attacks is complicated further by the matter of discerning whether the attacks really are attacks or just healthy and likely desired increases in website traffic.^ This sounds like a complicated attack on the Internet, and it is.
  • Crypto-Gram: February 15, 2000 12 September 2009 12:012 UTC www.schneier.com [Source type: FILTERED WITH BAYES]

^ Exposure of degradation-of-service attacks is complicated further by the matter of discerning whether the attacks really are attacks or just healthy and likely desired increases in website traffic.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ By initiating stealthy attacks, attackers can subtly increase the traffic loads without triggering DDoS protection thresholds [9],[10].
  • Cloud Computing Security: From DDoS (Distributed Denial Of Service) to EDoS (Economic Denial of Sustainability) | Rational Survivability 22 September 2009 16:10 UTC www.rationalsurvivability.com [Source type: General]

[15]

Unintentional denial of service

Aka VIPDoS
.This describes a situation where a website ends up denied, not due to a deliberate attack by a single individual or group of individuals, but simply due to a sudden enormous spike in popularity.^ This describes a situation where a website ends up denied, not due to a deliberate attack by a single individual or group of individuals, but simply due to a sudden enormous spike in popularity.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ NeuStar's UltraDNS service, used by many important businesses and organizations worldwide, has been the target of a distributed denial of service (DDoS) attack on Tuesday, making several popular websites hard to reach or completely inaccessible.
  • denial of service - news tag - Softpedia 19 January 2010 18:018 UTC news.softpedia.com [Source type: News]

^ Thousands of exploited, worm-ridden boxes - "drones" on the end of DSL lines or poorly secured servers are deployed by an attacker to attack a single destination.
  • Denial of service attack victim speaks out | CIO Insights | silicon.com 19 January 2010 18:018 UTC www.silicon.com [Source type: General]

.This can happen when an extremely popular website posts a prominent link to a second, less well-prepared site, for example, as part of a news story.^ This can happen when an extremely popular website posts a prominent link to a second, less well-prepared site, for example, as part of a news story.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Under normal operations this can happen several thousand times per second — well within the capabilities of even low end CPUs.
  • Preventing Denial of Service Attacks - O'Reilly Media 19 January 2010 18:018 UTC onlamp.com [Source type: General]

^ I do not provide links to vulnerability exploitation code on this site; if you wish to examine this program, you'll have to figure out how to download it from the BugTraq posting yourself.
  • Distributed Denial of Service Attack: January-April 2004 19 January 2010 18:018 UTC www.fourmilab.ch [Source type: FILTERED WITH BAYES]

.The result is that a significant proportion of the primary site's regular users — potentially hundreds of thousands of people — click that link in the space of a few hours, having the same effect on the target website as a DDoS attack.^ There are a number of steps that sites can take to reduce the effect if targeted by a DDOS attack.
  • AusCERT - Distributed Denial of Service Attacks 19 January 2010 18:018 UTC www.auscert.org.au [Source type: FILTERED WITH BAYES]

^ The result is that a significant proportion of the primary site's regular users — potentially hundreds of thousands of people — click that link in the space of a few hours, having the same effect on the target website as a DDoS attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Mitigating the effects of a DDoS attack .
  • DDOS 12 September 2009 12:012 UTC www.gss.co.uk [Source type: News]

.An example of this was when Michael Jackson died in 2009, websites such as Google and Twitter slowed down or even crashed.^ Such an attack, often generated by a network of compromised machines all directing traffic at a particular server or website, will overload and bring down a website.
  • Denial of service attack victim speaks out | CIO Insights | silicon.com 19 January 2010 18:018 UTC www.silicon.com [Source type: General]

^ This type of attack can even take down large sites such as Yahoo, Amazon and CNN, which are designed to handle millions of requests in a short amount of time.
  • Imperva Glossary | Distributed Denial of Service (DDoS) 22 September 2009 16:10 UTC www.imperva.com [Source type: News]
  • Imperva Glossary | Distributed Denial of Service (DDoS) 22 September 2009 16:016 UTC www.imperva.com [Source type: News]

^ August 6th, 2009 at 8:30 am PDT still down in italy and even facebook gave some connection problem about half an hour ago.
  • Oooh Dramatic! Twitter Gets DDOSed 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

.Many sites' servers thought the requests were from a virus or spyware trying to cause a Denial of Service attack, warning users that their queries looked like “automated requests from a computer virus or spyware application”[citation needed].^ Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]

^ Update 7: It’s a denial of service attack .
  • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

^ Securing against Denial of Service attacks .
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]

.News sites and link sites — sites whose primary function is to provide links to interesting content elsewhere on the Internet — are most likely to cause this phenomenon.^ News sites and link sites — sites whose primary function is to provide links to interesting content elsewhere on the Internet — are most likely to cause this phenomenon.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ These hosts requested nothing but the home page, which is highly anomalous, since that page on this site consists of nothing but a container for which any browser will, immediately upon receiving it, request the content pages to which it links.
  • Distributed Denial of Service Attack: January-April 2004 19 January 2010 18:018 UTC www.fourmilab.ch [Source type: FILTERED WITH BAYES]

^ As a result, blocking the prefixes that correspond to the attack sources results in blocking most Internet prefixes, thereby causing severe collateral damage.
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

.The canonical example is the Slashdot effect.^ The canonical example is the Slashdot effect.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Sites such as Digg, the Drudge Report, Fark, Something Awful, and the webcomic Penny Arcade have their own corresponding "effects", known as "the Digg effect", being "drudged", "farking", "goonrushing" and "wanging"; respectively.^ The site, which specializes in customizing items such as T-shirts, hats, and mugs, reported to members that it was experiencing problems due to the attack.
  • DDOS 12 September 2009 12:012 UTC www.gss.co.uk [Source type: News]

^ Have an intelligence gathering system within your organization so that such reports are centrally known so that trends can be spotted and responses devised.
  • Distributed Denial-Of-Service 19 January 2010 18:018 UTC www.garykessler.net [Source type: FILTERED WITH BAYES]

^ Indeed, having your site taken down by a flash crowd is probably a more common experience than having it DoS-ed -- so common it has acquired its own names: being Slashdotted or Farked, after the web sites that are common sources of flash crowds.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

.Routers have also been known to create unintentional DoS attacks, as both D-Link and Netgear routers have created NTP vandalism by flooding NTP servers without respecting the restrictions of client types or geographical limitations.^ The most obvious such attack is to DoS the NTP servers themselves.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ Routers have also been known to create unintentional DoS attacks, as both D-Link and Netgear routers have created NTP vandalism by flooding NTP servers without respecting the restrictions of client types or geographical limitations.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ DoS attacks can target servers, clients or routers.
  • Denial of Service Attacks: A Clear and Present Danger - Industry Trend or Event | Telecommunications | Find Articles at BNET 19 January 2010 18:018 UTC findarticles.com [Source type: News]

.Similar unintentional denials of service can also occur via other media, e.g.^ Unintentional denial of service .
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Similar unintentional denials of service can also occur via other media, e.g.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ A "denial of service" attacks occurs when hundreds of thousands of computers are directed to log onto a particular site simultaneously, causing it to crash under the weight of requests.
  • Telegraph website targeted in mystery attack by hackers - Times Online 19 January 2010 18:018 UTC technology.timesonline.co.uk [Source type: News]

when a .URL is mentioned on television.^ URL is mentioned on television.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.If a server is being indexed by Google or another search engine during peak periods of activity, or does not have a lot of available bandwidth while being indexed, it can also experience the effects of a DoS attack.^ If a server is being indexed by Google or another search engine during peak periods of activity, or does not have a lot of available bandwidth while being indexed, it can also experience the effects of a DoS attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ A graph of activity on the Infowars server showing the DoS attack.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.prisonplanet.com [Source type: FILTERED WITH BAYES]

^ What can be done to just not experience DoS attacks?
  • Denial-of-service Attack | Developer Oracles 19 January 2010 18:018 UTC devoracles.com [Source type: General]
  • Distributed Denial Of Service Attack | Developer Oracles 19 January 2010 18:018 UTC devoracles.com [Source type: General]

.Legal action has been taken in at least one such case.^ Legal action has been taken in at least one such case.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ One example of such an action is the abolishment of flatrates and the network wide use of usage-based fees [33].
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

^ Scan your network for open ports on a regular basis using tools such as nmap or saint - any changes should be investigated and appropriate action taken.
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]
  • The World Wide Web Security FAQ - Securing against Denial of Service attacks 19 January 2010 18:018 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

.In 2006, Universal Tube & Rollform Equipment Corporation sued YouTube: massive numbers of would-be youtube.com users accidentally typed the tube company's URL, utube.com.^ In 2006, Universal Tube & Rollform Equipment Corporation sued YouTube: massive numbers of would-be youtube.com users accidentally typed the tube company's URL, utube.com.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Saturday December 02 2006, @09:11PM ( #17085618 ) ( http://www.gottahavacuppamocha.com/ ) How about linking to the correct url [everydns.net]?
  • Slashdot | EveryDNS Under Botnet DDoS Attack 19 November 2009 18:39 UTC slashdot.org [Source type: General]

.As a result, the tube company ended up having to spend large amounts of money on upgrading their bandwidth.^ As a result, the tube company ended up having to spend large amounts of money on upgrading their bandwidth.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Smurfing: The culprit sends a large amount of ICMP echo traffic at IP Broadcast addresses, all of it having a spoofed source address of a victim.
  • Denial Of Service Attacks : DDOS Attack & Network Attack 19 January 2010 18:018 UTC www.streetdirectory.com [Source type: General]

^ You can fit more small packets in a particular amount of bandwidth than you can large packets.
  • Preventing Denial of Service Attacks - O'Reilly Media 19 January 2010 18:018 UTC onlamp.com [Source type: General]

[16]

Denial-of-Service Level II

.The goal of DoS L2 (possibly DDoS) attack is to cause a launching of a defense mechanism which blocks the network segment from which the attack originated.^ The goal of DoS L2 (possibly DDoS) attack is to cause a launching of a defense mechanism which blocks the network segment from which the attack originated.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]

^ A DDOS attack is a type of DOS attack.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]

^ The goal of DoS L2 (possibly DDoS) attack is to cause a launching of a defense mechanism which blocks the network segment from which the attack originated.In case of distributed attack or IP header modification (that depends on the kind of security behavior) it will fully block the attacked network from Internet, but without system crash.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.In case of distributed attack or IP header modification (that depends on the kind of security behavior) it will fully block the attacked network from Internet, but without system crash.^ The goal of DoS L2 (possibly DDoS) attack is to cause a launching of a defense mechanism which blocks the network segment from which the attack originated.In case of distributed attack or IP header modification (that depends on the kind of security behavior) it will fully block the attacked network from Internet, but without system crash.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Given that it takes hundreds of networked computers to take down a major Internet site in a denial-of-service attack, these networks could do significant damage.
  • Crypto-Gram: April 15, 2003 11 September 2009 4:11 UTC www.schneier.com [Source type: FILTERED WITH BAYES]

^ Increasingly, such attacks come from multiple, physically and network-topologically separated locations - a variation dubbed "Distributed" DoS attacks or DDoS attacks -...
  • Denial Of Service Attack Resources | ZDNet 11 September 2009 4:11 UTC updates.zdnet.com [Source type: General]

Blind denial of service

.Blind denial-of-service attacks are particularly pernicious.^ Update 7: It’s a denial of service attack .
  • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

^ Securing against Denial of Service attacks .
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]

^ Denial-of-service attack Denial-of-service attack .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.With a blind attack, the attacker has a significant advantage.^ With a blind attack, the attacker has a significant advantage.
  • BUZZWORD: Denial-of-service attack (DoS) 19 January 2010 18:018 UTC www.mediabuzz.com.sg [Source type: FILTERED WITH BAYES]
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ We have discussed partial solutions that reduce the effectiveness of attacks, and highlighted how some partial solutions can be taken advantage of by attackers to perpetrate alternative attacks.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ With a blind attack the attacker can use forged IP addresses, making it extremely difficult for the victim to filter out their packets.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.The attacker must be able to receive traffic from the victim, then the attacker must either subvert the routing fabric or use the attacker's own IP address.^ The attacker spoofs the requests with the victim's address.
  • Protecting Electronic Commerce From DistributedDenial-of-Service Attacks 19 January 2010 18:018 UTC www2002.org [Source type: FILTERED WITH BAYES]

^ The client uses this IP address for communication with t!
  • JIBC 22 September 2009 16:10 UTC www.arraydev.com [Source type: FILTERED WITH BAYES]

^ If the attacker must be able to receive traffic from the victim, then he must either subvert the routing fabric or use his own IP address.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Either provides an opportunity for the victim to track the attacker and/or filter out his traffic.^ Either provides an opportunity for the victim to track the attacker and/or filter out his traffic.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ This can be achieved by either overloading the ability of the victim server to handle incoming traffic or by sending requests that cause the victim server to behave unpredictably, possibly hanging or crashing the server.
  • Imperva Glossary | Denial of Service (DoS) 19 January 2010 18:018 UTC www.imperva.com [Source type: News]

^ Likewise, the attacker's service provider may do egress filtering that prevents forged source IP addresses.
  • Denial of Service via Algorithmic Complexity Attacks 19 January 2010 18:018 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]
  • Denial of Service via Algorithmic Complexity Attacks 22 September 2009 16:016 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]

.With a blind attack the attacker uses a forged IP addresses, making it extremely difficult for the victim to filter out those packets.^ This filters out the most commonly used spoofed source address.
  • Denial Of Service Attacks Explained And Prevention - Forums 19 January 2010 18:018 UTC www.governmentsecurity.org [Source type: General]

^ With a blind attack the attacker can use forged IP addresses, making it extremely difficult for the victim to filter out their packets.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ N]] Add IP addresses to list of attack victims.
  • SANS: Intrusion Detection FAQ: The "stacheldraht" Distributed Denial of Service Attack Tool 22 September 2009 16:10 UTC www.sans.org [Source type: FILTERED WITH BAYES]
  • dod1.htm: denial of service attack tools 11 September 2009 4:11 UTC www.crazyboy.com [Source type: Reference]

.The TCP SYN flood attack is an example of a blind attack.^ The attack itself is a SYN Flooding or a Smurf Attack.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ TCP SYN constant rate flood attack .
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

^ The TCP SYN flood attack is an example of a blind attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Designers should make every attempt possible to prevent blind denial of service attacks.^ Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC weblogs.asp.net [Source type: General]

^ Denial of service attacks .
  • Denial of service attacks - ServerBeach Forums 19 January 2010 18:018 UTC forums.serverbeach.com [Source type: General]

^ Denial of service attacks - ServerBeach Forums .
  • Denial of service attacks - ServerBeach Forums 19 January 2010 18:018 UTC forums.serverbeach.com [Source type: General]

[17]

Incidents

.
  • The first major attack involving DNS servers as reflectors occurred in January 2001. The target was Register.com.^ Many of the routing attacks can also be used against DNS servers by targeting the routing for the server.
    • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

    ^ The first major attack involving DNS servers as reflectors occurred in January 2001.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ Major DNS DOS attack .
    • DreamHost Status » Blog Archive » Major DNS DOS attack 19 January 2010 18:018 UTC www.dreamhoststatus.com [Source type: FILTERED WITH BAYES]

    [18] .This attack, which forged requests for the MX records of AOL.com (to amplify the attack) lasted about a week before it could be traced back to all attacking hosts and shut off.^ If so all communication to or from the host can be turned off.
    • Introduction to Denial of Service 22 September 2009 16:016 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

    ^ This attack, which forged requests for the MX records of AOL.com (to amplify the attack) lasted about a week before it could be traced back to all attacking hosts and shut off.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ According to this article, "Some are believed to have given into the criminals’ demands until, eventually, investigators traced the attack back to Russia and arrests were made."
    • Top 4 Tips to Fight Off Botnet Denial of Service Attacks | NetworkWorld.com Community 19 January 2010 18:018 UTC www.networkworld.com [Source type: General]

    .It used a list of tens of thousands of DNS records that were a year old at the time of the attack.
  • In February, 2001, the Irish Government's Department of Finance server was hit by a denial of service attack carried out as part of a student campaign from NUI Maynooth.^ It used a list of tens of thousands of DNS records that were a year old at the time of the attack.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ Denial-of-service attacks and the law .
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ BuzzFeed was hit with a denial of service attack, which works by overwhelming your servers with traffic.
    • DoS Attacks Drop - Denial Of Service Attacks: Pics, Videos, Links, News 19 January 2010 18:018 UTC www.buzzfeed.com [Source type: FILTERED WITH BAYES]
    • Anatomy Of A Denial Of Service Attack - Denial Of Service Attacks: Pics, Videos, Links, News 19 January 2010 18:018 UTC www.buzzfeed.com [Source type: FILTERED WITH BAYES]

    The Department officially complained to the University authorities and a number of students were disciplined..January 2009" style="white-space:nowrap;">[citation needed]
  • In July 2002, the Honeynet Project Reverse Challenge was issued.^ January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 .
    • Open Climate Science or Denial of Service attacks? | Serendipity 19 January 2010 18:018 UTC www.easterbrook.ca [Source type: FILTERED WITH BAYES]

    ^ January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 IT Topics .
    • Burying the truth? Boycott Novell hit by Denial of Service attack - Computerworld Blogs 19 January 2010 18:018 UTC blogs.computerworld.com [Source type: General]

    ^ In July 2002, the Honeynet Project Reverse Challenge was issued.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    [19] .The binary that was analyzed turned out to be yet another DDoS agent, which implemented several DNS related attacks, including an optimized form of a reflection attack.
  • On two occasions to date, attackers have performed DNS Backbone DDoS Attacks on the DNS root servers.^ An alternative form of attack amplifier is typified by a DNS reflection attack.
    • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

    ^ DdoS agents and controlled by the attacker .
    • http://www.ufsdump.org/papers/uuasc-november-ddos.html 19 January 2010 18:018 UTC www.ufsdump.org [Source type: FILTERED WITH BAYES]

    ^ Some early DDoS programs implemented a distributed form of this attack.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    .Since these machines are intended to provide service to all Internet users, these two denial of service attacks might be classified as attempts to take down the entire Internet, though it is unclear what the attackers' true motivations were.^ In all seriousness though, it’s like the Internet is momentarily down.
    • Oooh Dramatic! Twitter Gets DDOSed 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

    ^ Update 7: It’s a denial of service attack .
    • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

    ^ Securing against Denial of Service attacks .
    • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]

    .The first occurred in October 2002 and disrupted service at 9 of the 13 root servers.^ The first occurred in October 2002 and disrupted service at 9 of the 13 root servers.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ The first major attack involving DNS servers as reflectors occurred in January 2001.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ A distributed denial of service attack (DDoS) occurs when multiple systems flood the bandwidth or resources of a targeted system, usually one or more web servers.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    .The second occurred in February 2007 and caused disruptions at two of the root servers.^ The second architecture also eliminates root server.
    • JIBC 22 September 2009 16:10 UTC www.arraydev.com [Source type: FILTERED WITH BAYES]

    ^ The second occurred in February 2007 and caused disruptions at two of the root servers.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ One hour of pre-computed CPU work, on the client, can cause almost two hours of online work for a server.
    • Denial of Service via Algorithmic Complexity Attacks 19 January 2010 18:018 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]
    • Denial of Service via Algorithmic Complexity Attacks 22 September 2009 16:016 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]

    [20]
  • .
  • In February 2007, more than 10,000 online game servers in games such as Return to Castle Wolfenstein, Halo, Counter-Strike and many others were attacked by "RUS" hacker group.^ Some attacks are more critical than others.

    ^ In February 2007, more than 10,000 online game servers in games such as Return to Castle Wolfenstein, Halo, Counter-Strike and many others were attacked by "RUS" hacker group.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ This attack is more a concept than a real attack.
    • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

    .The DDoS attack was made from more than a thousand computer units located in the republics of the former Soviet Union, mostly from Russia, Uzbekistan and Belarus.^ The DDoS attack was made from more than a thousand computer units located in the republics of the former Soviet Union, mostly from Russia, Uzbekistan and Belarus.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ It has more than 1700 Signatures Rules with online update that identify and block almost all known attacks such as DDOS attack and Sql Injection attack.
    • Ddos downloads at VicMan 12 September 2009 12:012 UTC www.vicman.net [Source type: General]

    ^ TFN2K mixed attack 5 computers running a http-attack with the mixed database and 3 computers doing a TFN2K mixed attack 3 computers running a http-attack with the mixed database and 5 computers doing a TFN2K SYN-flood attack 5 computers running a http-attack with the mixed database and 3 computers doing a mixed TFN2K SYN-flood attack Traffic measuring was done by inserting a hub at different locations in the test network.
    • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

    .Minor attacks are still continuing to be made today.^ Minor attacks are still continuing to be made today.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ Today saw a new recent high for the second wave of the attack, with the divergence between hits per hour and unique IP addresses still in evidence.
    • Distributed Denial of Service Attack: January-April 2004 19 January 2010 18:018 UTC www.fourmilab.ch [Source type: FILTERED WITH BAYES]

    .August 2007" style="white-space:nowrap;">[citation needed]
  • In the weeks leading up to the five-day 2008 South Ossetia war, a DDoS attack directed at Georgian government sites containing the message: “win+love+in+Rusia" effectively overloaded and shut down multiple Georgian servers.^ As for the DDoS attack, Schestowitz wrote, the site "has been under DDoS attack for 3 days now.
    • Burying the truth? Boycott Novell hit by Denial of Service attack - Computerworld Blogs 19 January 2010 18:018 UTC blogs.computerworld.com [Source type: General]

    ^ Sites that have been harmed by DDOS's in the past have been consistently attacked for days or weeks at a time.
    • Conerning The On Going Denial of Service Attacks Today. - dslreports.com 19 January 2010 18:018 UTC www.dslreports.com [Source type: General]

    ^ In the weeks leading up to the five-day 2008 South Ossetia war, a DDoS attack directed at Georgian government sites containing the message: “win+love+in+Rusia" effectively overloaded and shut down multiple Georgian servers.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    .Websites targeted included the Web site of the Georgian president, Mikhail Saakashvili, rendered inoperable for 24 hours, and the National Bank of Georgia.^ Websites targeted included the Web site of the Georgian president, Mikhail Saakashvili, rendered inoperable for 24 hours, and the National Bank of Georgia.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ A DDoS attack involves sending large amounts of data that renders Web servers unusable by obstructing communication between the intended server and the target.
    • Urgent-Massive DDOS Attack! 12 September 2009 12:012 UTC forums.comodo.com [Source type: General]

    ^ An attacker might have looked at your corporate Web site and guessed some user names based on e-mail addresses included on your public Web site.
    • Prevent Denial of Service Attacks with Lockout Guard 19 January 2010 18:018 UTC www.isaserver.org [Source type: General]

    While heavy suspicion was placed on Russia for orchestrating the attack through a proxy, the St. Petersburg-based criminal gang known as the Russian Business Network, or R.B.N, the Russian government denied the allegations, stating that it was possible that individuals in Russia or elsewhere had taken it upon themselves to start the attacks.[21]
  • .
  • During the 2009 Iranian election protests, foreign activists seeking to help the opposition engaged in DDoS attacks against Iran's government.^ During the 2009 Iranian election protests, foreign activists seeking to help the opposition engaged in DDoS attacks against Iran's government.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ This was during the height of the anti-government protests in Iran, much information was being disseminated to the world via Twitter, and the maintenance window, in the middle of the night in California, would have been prime daylight hours in Tehran.
    • Denial-of-Service Attack Knocks Twitter Offline (Updated) | Epicenter | Wired.com 19 January 2010 18:018 UTC www.wired.com [Source type: General]

    ^ Critics claimed that the DDoS attacks also cut off internet access for protesters inside Iran; activists countered that, while this may have been true, the attacks still hindered President Mahmoud Ahmadinejad's government enough to aid the opposition.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    .The official website of the Iranian government (ahmedinejad.ir) was rendered inaccessible on several occasions.^ The official website of the Iranian government ( ahmedinejad.ir ) was rendered inaccessible on several occasions.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ Hacktivists DDoS 10 Downing St site UK government website 10 Downing Street was briefly rendered inaccessible yesterday after a co-ordinated denial of service attack protesting the Prime Minster's role in the conflict.
    • DDOS 12 September 2009 12:012 UTC www.gss.co.uk [Source type: News]

    [22] .Critics claimed that the DDoS attacks also cut off internet access for protesters inside Iran; activists countered that, while this may have been true, the attacks still hindered President Mahmoud Ahmadinejad's government enough to aid the opposition.
  • On June 25, 2009, the day Michael Jackson died, the spike in searches related to Michael Jackson was so big that Google News initially mistook it for an automated attack.^ During the 2009 Iranian election protests, foreign activists seeking to help the opposition engaged in DDoS attacks against Iran's government.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ Critics claimed that the DDoS attacks also cut off internet access for protesters inside Iran; activists countered that, while this may have been true, the attacks still hindered President Mahmoud Ahmadinejad's government enough to aid the opposition.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ DDoS attacks still biggest threat .
    • DDOS 12 September 2009 12:012 UTC www.gss.co.uk [Source type: News]

    .As a result, for about 25 minutes, when some people searched Google News they saw a "We're sorry" page before finding the articles they were looking for.^ We're also *very* interested in any information about this tool (since it appears to be new, and quite effective).
    • dod1.htm: denial of service attack tools 11 September 2009 4:11 UTC www.crazyboy.com [Source type: Reference]

    ^ Now how many people here saw the news that the Pentagon puters were hacked?
    • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]

    ^ (I would find it annoying to have to type my username and password in every time I wanted to see another New York Times article.
    • Crypto-Gram: February 15, 2000 12 September 2009 12:012 UTC www.schneier.com [Source type: FILTERED WITH BAYES]

    [23]
  • .
  • June 2009 the P2P site The Pirate Bay was rendered inaccessible due to a DDoS attack.^ June of 2009 the famous P2P site known as The Pirate Bay was rendered inaccessable due to a DDoS attack.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ During the 2009 Iranian election protests, foreign activists seeking to help the opposition engaged in DDoS attacks against Iran's government.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ A DDoS attack involves sending large amounts of data that renders Web servers unusable by obstructing communication between the intended server and the target.
    • Urgent-Massive DDOS Attack! 12 September 2009 12:012 UTC forums.comodo.com [Source type: General]

    .This was most likely provoked by the recent sellout to Global Gaming Factory X AB, which was seen as a "take the money and run" solution to the website's legal issues.^ This was most likely provoked by the recent sellout to Gaming Factory X AB and seen as a "take the money and run" solution to the website's legal issues.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ When Studio Traffic has a problem, like running out of money, there is no way of communicating with all the members or any members of the forums.
    • Does anyone know how to DDos? 12 September 2009 12:012 UTC www.talkgold.com [Source type: FILTERED WITH BAYES]

    ^ Many experts think that the only durable solution to this problem is to globally improve the security on all hosts in the Internet to take attackers the possibility to use other hosts for running daemons.
    • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

    [24] .In the end, due to the buyers' financial troubles, the site was not sold.
  • Multiple waves of July 2009 cyber attacks targeted a number of major websites in South Korea and the United States.^ Given that it takes hundreds of networked computers to take down a major Internet site in a denial-of-service attack, these networks could do significant damage.
    • Crypto-Gram: April 15, 2003 11 September 2009 4:11 UTC www.schneier.com [Source type: FILTERED WITH BAYES]

    ^ This describes a situation where a website ends up denied, not due to a deliberate attack by a single individual or group of individuals, but simply due to a sudden enormous spike in popularity.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    ^ Websites targeted included the Web site of the Georgian president, Mikhail Saakashvili, rendered inoperable for 24 hours, and the National Bank of Georgia.
    • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

    .The attacker used botnet and file update through internet is known to assist its spread.^ First, the hash function being used must be deterministic and known to the attacker.
    • Denial of Service via Algorithmic Complexity Attacks 19 January 2010 18:018 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]
    • Denial of Service via Algorithmic Complexity Attacks 22 September 2009 16:016 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]

    ^ For remote administration and content updates, use a remote login and file copy program with good encryption, such as ssh http://www.openssh.org/ .
    • Distributed Denial of Service Attacks 12 September 2009 12:012 UTC www.linuxsecurity.com [Source type: FILTERED WITH BAYES]

    ^ Is there an easy way that I can install the RPM file through the WebHostManager (where do I put the file) or does this need to be done through the shell using the .gz file.
    • Denial of service attacks - ServerBeach Forums 19 January 2010 18:018 UTC forums.serverbeach.com [Source type: General]

    .As it turns out, a computer trojan was coded to scan for existing MyDoom bots.^ Scans your computer for malicious software (Malware), including Trojan Horses, Dialers, Worms, Spyware, Adware and more.
    • Ddos downloads at VicMan 12 September 2009 12:012 UTC www.vicman.net [Source type: General]

    .MyDoom was a worm in 2004, and in July around 20,000-50,000 were present.^ When it was discovered in January 2004, MyDoom quickly became the fastest-spreading e-mail worm in Internet history.
    • Urgent-Massive DDOS Attack! 12 September 2009 12:012 UTC forums.comodo.com [Source type: General]

    ^ Update: 2004-02-20 00:50 UTC .
    • Distributed Denial of Service Attack: January-April 2004 19 January 2010 18:018 UTC www.fourmilab.ch [Source type: FILTERED WITH BAYES]

    MyDoom has a backdoor, which the DDoS bot could exploit. .Since then, the DDoS bot removed itself, and completely formatted the hard drives.^ Usually, since the malware is installed itself as a service, you have to run the malware remover in Windows’s safe mode.
    • Denial-of-service Attack | Developer Oracles 19 January 2010 18:018 UTC devoracles.com [Source type: General]

    .Most of the bots originated from China, and North Korea.
  • On August 6, 2009 several social networking sites, including Twitter, Facebook, Livejournal, and Google blogging pages were hit by DDoS attacks, apparently aimed at Georgian blogger "Cyxymu". Although Google came through with only minor set-backs, these attacks left Twitter crippled for hours and Facebook did eventually restore service although some users still experienced trouble.^ Whole site is unavailable - including Twitter blog .
    • Denial-of-Service Attack Knocks Twitter Offline (Updated) | Epicenter | Wired.com 19 January 2010 18:018 UTC www.wired.com [Source type: General]

    ^ Twitter, Facebook attack targeted one user .
    • Twitter, Facebook attack targeted one user | InSecurity Complex - CNET News 19 January 2010 18:018 UTC news.cnet.com [Source type: FILTERED WITH BAYES]
    • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

    ^ Twitter victim of denial-of-service attack .
    • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

    .Twitter's Site latency has continued to improve, however some web requests continue to fail.^ The barrage of connection requests overwhelms the target sites, making it so that legitimate Web traffic can't get through.
    • Twitter, Facebook attack targeted one user | InSecurity Complex - CNET News 19 January 2010 18:018 UTC news.cnet.com [Source type: FILTERED WITH BAYES]

    ^ However, AusCERT is aware that some Australian sites are experiencing DOS problems.
    • AusCERT - Distributed Denial of Service Attacks 19 January 2010 18:018 UTC www.auscert.org.au [Source type: FILTERED WITH BAYES]

    ^ At a recent hearing on computer security in the Senate, some experts said the Web sites that were recently hit with denial-of-service attacks should have expected such attacks and prepared for them.
    • MSIS 491 -- Electronic Commerce 19 January 2010 18:018 UTC www.umsl.edu [Source type: News]

    [25][26][27]

Performing DoS-attacks

.A wide array of programs are used to launch DoS-attacks.^ The programs used to launch the attacks had been identified and analyzed.
  • Internet Denial of Service Attacks and the Federal Response 19 January 2010 18:018 UTC publius.cdt.org [Source type: Original source]

^ In order not to be traced, the perpetrators will break into unsecured computers on the internet, hide rogue DDoS programs on them, and then use them as unwitting accomplices to anonymously launch the attack.
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]
  • The World Wide Web Security FAQ - Securing against Denial of Service attacks 19 January 2010 18:018 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

^ DoS and DDoS attacks usually use a limited number of well known attacks with names like smurf, teardrop or SYN-Flood.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

.Most of these programs are completely focused on performing DoS-attacks, while others are also true Packet injectors, thus able to perform other tasks as well.^ For most of the attacks, these packets are directed at the victim machine.
  • Distributed Denial of Service Attacks 12 September 2009 12:012 UTC www.linuxsecurity.com [Source type: FILTERED WITH BAYES]

^ Most of these programs are completely focused on performing DoS-attacks, while others are also true Packet injectors, thus able to perform other tasks as well.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Performing DoS-attacks .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[28]

Prevention and response

Surviving attacks

.The investigative process should begin immediately after the DoS attack begins.^ Begins DoS attack.
  • SANS: Intrusion Detection FAQ: The "stacheldraht" Distributed Denial of Service Attack Tool 22 September 2009 16:10 UTC www.sans.org [Source type: FILTERED WITH BAYES]
  • dod1.htm: denial of service attack tools 11 September 2009 4:11 UTC www.crazyboy.com [Source type: Reference]

^ The investigative process should begin immediately after the DoS attack begins.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ A Google representative offered this statement: "We are aware that a handful of non-Google sites were impacted by a DoS attack this morning and are in contact with some affected companies to help investigate this attack.
  • Twitter, Facebook attack targeted one user | InSecurity Complex - CNET News 19 January 2010 18:018 UTC news.cnet.com [Source type: FILTERED WITH BAYES]

.There will be multiple phone calls, callbacks, emails, pages and faxes between the victim organization, one's provider, and others involved.^ There will be multiple phone calls, callbacks, emails, pages and faxes between the victim organization, one's provider, and others involved.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ April 8th, 2007 at 3:42 am Tom Says: Yep, one of my sites (and it’s email) is still unreachable, but one of my other ones is fine now.
  • DreamHost Status » Blog Archive » Major DNS DOS attack 19 January 2010 18:018 UTC www.dreamhoststatus.com [Source type: FILTERED WITH BAYES]

^ The cracker then sends UDP packets to the port 19 ( chargen ) to one of the "victims" spoofing the IP address and the source port from the other one.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

.This can be a very time consuming process.^ This can be a very time consuming process.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Comprehensive testing is obviously a highly complex, time-consuming process, calling for more efficient and comprehensive approaches.
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

^ While not as expensive as SYN processing, this still takes time and consumes outbound bandwidth.
  • Preventing Denial of Service Attacks - O'Reilly Media 19 January 2010 18:018 UTC onlamp.com [Source type: General]

.It has taken some very large networks with plenty of resources several hours to halt a DoS attack.^ It has taken some very large networks with plenty of resources several hours to halt a DoS attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Denial of service: Fighting back Review: Test shows there are several varied, viable options that help defend your network against attacks.
  • DDoS (distributed denial of service) 22 September 2009 16:10 UTC www.networkworld.com [Source type: News]

^ TFN2K mixed attack 5 computers running a http-attack with the mixed database and 3 computers doing a TFN2K mixed attack 3 computers running a http-attack with the mixed database and 5 computers doing a TFN2K SYN-flood attack 5 computers running a http-attack with the mixed database and 3 computers doing a mixed TFN2K SYN-flood attack Traffic measuring was done by inserting a hub at different locations in the test network.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

[citation needed]
.The easiest way to survive an attack is to have planned for the attack.^ The easiest way to survive an attack is to have planned for the attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Targets: the easiest way to frustrate a smurf attack is to filter for echo reply packets at the border routers and drop them.
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]
  • The World Wide Web Security FAQ - Securing against Denial of Service attacks 19 January 2010 18:018 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

.Good contacts with your ISP and some security providers and CERT are essential.^ Contact your ISP to find out.
  • Preventing Denial of Service Attacks - O'Reilly Media 19 January 2010 18:018 UTC onlamp.com [Source type: General]

^ The client provides the ISP client locator to an e-merchant that the client wishes to access as a VIP. This may be implemented by uploading the ISP client locator to a secure Web site maintained by the e-merchant.
  • Protecting Electronic Commerce From DistributedDenial-of-Service Attacks 19 January 2010 18:018 UTC www2002.org [Source type: FILTERED WITH BAYES]

^ These papers provide useful background information, with [ CERT-1 ] in particular providing some pragmatic advice.
  • AusCERT - Distributed Denial of Service Attacks 19 January 2010 18:018 UTC www.auscert.org.au [Source type: FILTERED WITH BAYES]

.Also having a separate emergency block of IP addresses for critical servers with a separate route can be invaluable.^ Having a separate emergency block of IP addresses for critical servers with a separate route can be invaluable.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ A separate route (perhaps a DSL) is not that extravagant, and it can be used for load balancing or sharing under normal circumstances and switched to emergency mode in the event of an attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ If the source IP address being processed by a router does not have a route that points back to the same interface on which the packet arrived, the router drops the packet.
  • AusCERT - Distributed Denial of Service Attacks 19 January 2010 18:018 UTC www.auscert.org.au [Source type: FILTERED WITH BAYES]

.A separate route (perhaps a DSL) is not that extravagant, and it can be used for load balancing or sharing under normal circumstances and switched to emergency mode in the event of an attack.^ A separate route (perhaps a DSL) is not that extravagant, and it can be used for load balancing or sharing under normal circumstances and switched to emergency mode in the event of an attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ If this happens, the firewall classifies it as a DoS attack and switches to Emergency Mode.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The load-balancer is another attack target.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

[citation needed]
.Filtering is often ineffective[29], as the route to the filter will normally be swamped so only a trickle of traffic will survive.^ Filtering is often ineffective, as the route to the filter will normally be swamped so only a trickle of traffic will survive.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Large number of attack sources : Each hardware router has only a limited number of filters that can block traffic without degrading the router's performance (i.e., filters operating at wire speed).
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

^ The former requires 10 million filters; the latter requires only 10 filters, but sacrifices most good traffic going to the victims.
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

.However, by using an extremely resilient stateful packet filter that will inexpensively drop any unwanted packets, surviving a DoS attack becomes much easier.^ However, by using an extremely resilient stateful packet filter that will inexpensively drop any unwanted packets, surviving a DoS attack becomes much easier.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Maybe we can adapt defenses against flooding attacks in other media, like email and DNS. Maybe not; much of the information used on the Internet isn't available with POTS. .
  • Skype Journal: Using Skype for a POTS Denial of Service Attack 19 January 2010 18:018 UTC www.skypejournal.com [Source type: General]

^ These schemes will work as long as the DoS attacks are something that can be prevented by using them.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.September 2008" style="white-space:nowrap;">[citation needed] When such a high performance packet filtering server is attached to an ultra-high bandwidth connection (preferably an internet backbone), communication with the outside world will be unimpaired so long as not all of the available bandwidth is saturated, and performance behind the packet filter will remain normal as long as the packet filter drops all DoS packets.^ When such a high performance packet filtering server is attached to an ultra-high bandwidth connection (preferably an internet backbone), communication with the outside world will be unimpaired so long as not all of the available bandwidth is saturated, and performance behind the packet filter will remain normal as long as the packet filter drops all DoS packets.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ If a server is being indexed by Google or another search engine during peak periods of activity, or does not have a lot of available bandwidth while being indexed, it can also experience the effects of a DoS attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ However, by using an extremely resilient stateful packet filter that will inexpensively drop any unwanted packets, surviving a DoS attack becomes much easier.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[30] .It should be noted however, that in this case the victim of the DoS attack still would need to pay for the excessive bandwidth.^ It should be noted however, that in this case the victim of the DoS attack still would need to pay for the excessive bandwidth.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ However, by using an extremely resilient stateful packet filter that will inexpensively drop any unwanted packets, surviving a DoS attack becomes much easier.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Ultimately, the question is whether the victim will accept enough attack-input for the worst-case behavior to manifest itself.
  • Denial of Service via Algorithmic Complexity Attacks 19 January 2010 18:018 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]
  • Denial of Service via Algorithmic Complexity Attacks 22 September 2009 16:016 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]

.The price of service unavailability thus needs to be weighed against the price of truly exorbitant bandwidth/traffic.^ The price of service unavailability thus needs to be weighed against the price of truly exorbitant bandwidth/traffic.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Thus, defending against DoS is not about preventing all possible attacks, but rather is largely a question of raising the bar sufficiently high for malicious traffic.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ Thus, the attacker can cause forwarding performance to degrade to the point where service is effectively denied to the legitimate traffic traversing the firewall.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

Firewalls

.Firewalls have simple rules such as to allow or deny protocols, ports or IP addresses.^ Firewall have simple rules such as to allow or deny protocols, ports or IP addresses.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Protocols should, whenever possible, avoid including IP addresses or hostnames within protocol payloads as addresses to which subsequent messaging should be sent.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ Whereas the source port spoofing only works if the agent is running as a root privileged process, the author has added provisions for packet flooding using the UDP protocol and with the correct source address in the case the process is running as a simple user process.
  • Analyzing Distributed Denial Of Service Tools: The Shaft Case 22 September 2009 16:10 UTC www.usenix.org [Source type: FILTERED WITH BAYES]

.Some DoS attacks are too complex for today's firewalls, e.g.^ Some DoS attacks are too complex for today's firewalls, e.g.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Although software patching defends against some attacks, it fails to safeguard against DoS flooding attacks, which exploit the unregulated forwarding of Internet packets.
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

^ Anyone who can learn the firewall's algorithms may be able to mount DoS attacks against those systems.
  • Denial of Service via Algorithmic Complexity Attacks 19 January 2010 18:018 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]
  • Denial of Service via Algorithmic Complexity Attacks 22 September 2009 16:016 UTC www.cs.rice.edu [Source type: FILTERED WITH BAYES]

if there is an attack on port .80 (web service), firewalls cannot prevent that attack because they cannot distinguish good traffic from DoS attack traffic.^ Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]

^ Go Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]

^ On the contrary, congestive DoS attacks cannot be similarly prevented.
  • Protecting Electronic Commerce From DistributedDenial-of-Service Attacks 19 January 2010 18:018 UTC www2002.org [Source type: FILTERED WITH BAYES]

.Additionally, firewalls are too deep in the network hierarchy.^ Additionally, firewalls are too deep in the network hierarchy.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Routers may be affected even before the firewall gets the traffic.^ Routers may be affected even before the firewall gets the traffic.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ This may be used as an attack on webservers, load balancers or even firewalls, if they run one of the named operating systems.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

^ Identifying that router may identify the Internet carrier that passed the traffic to you, if you don't have a complex internet of your own, within your own organization.
  • Distributed Denial of Service Attacks 12 September 2009 12:012 UTC www.linuxsecurity.com [Source type: FILTERED WITH BAYES]

.Nonetheless, firewalls can effectively prevent users from launching simple flooding type attacks from machines behind the firewall.^ Nonetheless, firewalls can effectively prevent users from launching simple flooding type attacks from machines behind the firewall.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Introduction A Denial-of-Service (DoS) attack is an attack in which one or more machines target a victim and attempt to prevent the victim from doing useful work.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ As an example: during our experiments some misconfigured SYN-flood attack overloaded our university's firewall and blocked most in- and outgoing traffic.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

.Some stateful firewalls like OpenBSD's pF, can act as a proxy for connections, the handshake is validated (with the client) instead of simply forwarding the packet to the destination.^ Instead, the attacker acts as a 'puppet master,' instructing clients of large peer-to-peer file sharing hubs to disconnect from their peer-to-peer network and to connect to the victim’s website instead.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Furthermore they are typically protected by firewall systems that block the known attacks that are based on malformed packets like jolt2 does.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

^ Like DOS , DDOS also tries to deny the important services running on a server by broadcasting packets to the destination server in a way that the Destination server cannot handle it.
  • Preventing DDoS Attacks - The Community's Center for Security 22 September 2009 16:10 UTC www.linuxsecurity.com [Source type: General]

.It is available for other BSDs as well.^ A similar ability is present in OpenBSD's pF, which is available for other BSDs as well.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

In that context, it is called "synproxy".[citation needed]

Switches

.Most switches have some rate-limiting and ACL capability.^ Similar to switches, routers have some rate-limiting and ACL capability.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Most switches have some rate-limiting and ACL capability.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ If the total number of new D-proxies (spoofed and valid) exceeds the unknown rate limit, some valid D-proxies are dropped.
  • Cisco GSS Command Reference (Software Version 2.0) - DDoS Module Configuration Mode Commands  [Cisco ACE GSS 4400 Series Global Site Selector Appliances] - Cisco Systems 12 September 2009 12:012 UTC www.cisco.com [Source type: Reference]

.Some switches provide automatic and/or system-wide rate limiting, traffic shaping, delayed binding (TCP splicing), deep packet inspection and Bogon filtering (bogus IP filtering) to detect and remediate denial of service attacks through automatic rate filtering and WAN Link failover and balancing.^ Update 7: It’s a denial of service attack .
  • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

^ Securing against Denial of Service attacks .
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]

^ Denial-of-service attack Denial-of-service attack .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[citation needed]
.These schemes will work as long as the DoS attacks are something that can be prevented by using them.^ These schemes will work as long as the DoS attacks are something that can be prevented by using them.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ However, by using an extremely resilient stateful packet filter that will inexpensively drop any unwanted packets, surviving a DoS attack becomes much easier.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ A wide array of programs are used to launch DoS-attacks.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.For example SYN flood can be prevented using delayed binding or TCP splicing.^ The TCP SYN flood attack is an example of a blind attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Use syn flooding.
  • Introduction to Denial of Service 22 September 2009 16:016 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

^ For example SYN flood can be prevented using delayed binding or TCP splicing.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Similarly content based DoS can be prevented using deep packet inspection.^ Similarly content based DoS can be prevented using deep packet inspection.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ However, by using an extremely resilient stateful packet filter that will inexpensively drop any unwanted packets, surviving a DoS attack becomes much easier.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ These schemes will work as long as the DoS attacks are something that can be prevented by using them.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Attacks originating from dark addresses or going to dark addresses can be prevented using Bogon filtering.^ Attacks originating from dark addresses or going to dark addresses can be prevented using Bogon filtering.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ However, by using an extremely resilient stateful packet filter that will inexpensively drop any unwanted packets, surviving a DoS attack becomes much easier.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ These schemes will work as long as the DoS attacks are something that can be prevented by using them.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Automatic rate filtering can work as long as you have set rate-thresholds correctly and granularly.^ Through the settings of the threshold and upper bound, the Cusum algorithm can trade off detection delay and false-alarm rates.
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

^ Thus, if V gw uses N filters filters, it achieves filtering rate N filters / T tmp flows/sec, filtering capacity N filters × T long / T tmp flows and filtering gain For example, assume T tmp = 1 sec and T long = 10 min.
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

^ Note that A does not risk disconnection for not satisfying requests beyond the agreed rate -- a correctly functioning provider does not overload a customer with filtering requests and then disconnect the customer for failing to satisfy them.
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

.Wan-link failover will work as long as both links have DoS/DDoS prevention mechanism.^ Wan-link failover will work as long as both links have DoS/DDoS prevention mechanism.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ These schemes will work as long as the DoS attacks are something that can be prevented by using them.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Introduction A Denial-of-Service (DoS) attack is an attack in which one or more machines target a victim and attempt to prevent the victim from doing useful work.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

[citation needed]

Routers

.Similar to switches, routers have some rate-limiting and ACL capability.^ Similar to switches, routers have some rate-limiting and ACL capability.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Most switches have some rate-limiting and ACL capability.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ All of these routers can do ACL's at full packet rates.
  • Slashdot | EveryDNS Under Botnet DDoS Attack 19 November 2009 18:39 UTC slashdot.org [Source type: General]

.They, too, are manually set.^ They, too, are manually set.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Most routers can be easily overwhelmed under DoS attack.^ Most routers can be easily overwhelmed under DoS attack.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ For example, it would have been nice to see examples of system metrics from nodes or routers under DoS attack.
  • ProQuest Tech Books: Internet Denial of Service: Attack and Defense Mechanisms 19 January 2010 18:018 UTC proquest.safaribooksonline.com [Source type: Academic]

^ Most manufacturers have realized the importance of defense measures against DoS attacks.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

.If you add rules to take flow statistics out of the router during the DoS attacks, they further slow down and complicate the matter.^ Sorry kids, reality is, they would do a DOS attack to shut you down.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]

^ So it’s not only you they’re attacking.
  • The Official DreamHost Blog! » Massive DDOS Attack 19 January 2010 18:018 UTC blog.dreamhost.com [Source type: General]

^ FAQ: The ins and outs of DoS attacks .
  • DDOS 12 September 2009 12:012 UTC www.gss.co.uk [Source type: News]

Cisco IOS has features that prevents flooding, i.e. example settings.[31]

Application front end hardware

.Application front end hardware is intelligent hardware placed on the network before traffic reaches the servers.^ Application front end hardware .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Application front end hardware is intelligent hardware placed on the network before traffic reaches the servers.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ In processing network traffic, such an application uses these resources to do its intended task.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

.It can be used on networks in conjunction with routers and switches.^ It can be used on networks in conjunction with routers and switches.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The routing protocols themselves can be used to stage a DoS attack on a router or a network of routers.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ Set up egress filltering on the border routers, as perhaps not all TFN2K source addresses will be spoofed using internal network addresses.
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]
  • The World Wide Web Security FAQ - Securing against Denial of Service attacks 19 January 2010 18:018 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

.Application front end hardware analyzes data packets as they enter the system, and then identifies them as priority, regular, or dangerous.^ Application front end hardware .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Application front end hardware analyzes data packets as they enter the system, and then identifies them as priority, regular, or dangerous.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ With the help of the network analyzer Argus [1], spikes (see Figure 2) in the packet flows led to the discovery of the shaftnode agent on the compromised system within the local network.
  • Analyzing Distributed Denial Of Service Tools: The Shaft Case 22 September 2009 16:10 UTC www.usenix.org [Source type: FILTERED WITH BAYES]

.There are more than 25 bandwidth management vendors.^ There are more than 25 bandwidth management vendors.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Couple either scenario with the fact that there is more stuff out there for Windows than there is for the Mac, and the limitations of the Mac universe further constrict upon user potential.
  • Twitter, Facebook attack targeted one user | InSecurity Complex - CNET News 19 January 2010 18:018 UTC news.cnet.com [Source type: FILTERED WITH BAYES]

^ There are people who say there are more of these vulnerabilities for the Mac than there are for Windows.
  • Twitter, Facebook attack targeted one user | InSecurity Complex - CNET News 19 January 2010 18:018 UTC news.cnet.com [Source type: FILTERED WITH BAYES]

.Hardware acceleration is key to bandwidth management.^ Hardware acceleration is key to bandwidth management.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Look for granularity of bandwidth management, hardware acceleration, and automation while selecting an appliance.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Look for granularity of bandwidth management, hardware acceleration, and automation while selecting an appliance.^ Look for granularity of bandwidth management, hardware acceleration, and automation while selecting an appliance.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Hardware acceleration is key to bandwidth management.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[citation needed]

IPS based prevention

.Intrusion-prevention systems (IPS) are effective if the attacks have signatures associated with them.^ Intrusion-prevention systems (IPS) are effective if the attacks have signatures associated with them.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Intrusion-prevention system Black fax Cybercrime Dosnet Intrusion-detection system Network intrusion detection system Wireless signal jammer Zombie computer External links .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Intrusion-prevention systems which work on content recognition cannot block behavior based DoS attacks.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.However, the trend among the attacks is to have legitimate content but bad intent.^ However, the trend among the attacks is to have legitimate content but bad intent.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

.Intrusion-prevention systems which work on content recognition cannot block behavior-based DoS attacks.^ Intrusion-prevention systems which work on content recognition cannot block behavior based DoS attacks.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ On the contrary, congestive DoS attacks cannot be similarly prevented.
  • Protecting Electronic Commerce From DistributedDenial-of-Service Attacks 19 January 2010 18:018 UTC www2002.org [Source type: FILTERED WITH BAYES]

^ Intrusion-prevention systems (IPS) are effective if the attacks have signatures associated with them.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[citation needed]
.An ASIC based IPS can detect and block denial of service attacks because they have the processing power and the granularity to analyze the attacks and act like a circuit breaker in an automated way.^ Twitter victim of denial-of-service attack .
  • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

^ Twitter hit by denial of service attack .
  • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

^ Denial-of-service attacks and the law .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

[citation needed]
.A rate-based IPS (RBIPS) must analyze traffic granularly and continuously monitor the traffic pattern and determine if there is traffic anomaly.^ Again there is a timer and if this behavior is shown for a certain amount of time, a ipchains filter blocks traffic from that IP. .
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

^ Our solution to the problem of handling massive http overload requests is based on class based routing and active traffic monitoring.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

^ Such monitoring tools can be used to set a baseline of "normal" traffic, and can be used to detect aberrant flows and determine the type and source of the aberrant flows.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

.It must let the legitimate traffic flow while blocking the DoS attack traffic.^ It must let the legitimate traffic flow while blocking the DoS attack traffic.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ DoS attack traffic.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Attack gateway : Every time A gw completes a handshake, it spends 1 filter for T tmp seconds and causes 1 flow to be blocked.
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

[citation needed]

Prevention via proactive testing

.Test platforms such as Mu Dynamics' Service Analyzer are available to perform simulated denial-of-service attacks that can be used to evaluate defensive mechanisms such IPS, RBIPS, as well as the popular denial-of-service mitigation products from Arbor Networks.^ Such an attack is known as a Distributed Denial-of-Service (DDoS) attack.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ Twitter victim of denial-of-service attack .
  • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

^ Twitter hit by denial of service attack .
  • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

.An example of proactive testing of denial-of-service throttling capabilities in a switch was performed in 2008: The Juniper EX 4200 switch with integrated denial-of-service throttling was tested by Network Test and the resulting review was published in Network World.^ An example of proactive testing of denial-of-service throttling capabilities in a switch was published earlier this year: The Juniper EX 4200 switch with integrated denial-of-service throttling was tested by Network Test and the resulting review was published in Network World .
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The result of such a denial of service is to make a network unreachable.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ Network denial of service .
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

Blackholing/Sinkholing

.With blackholing, you send all the traffic which is sent to the attacked DNS or IP address to a "black hole" (null interface, non-existent server, ...^ The IP addresses of the root servers are well known to all resolvers.
  • JIBC 22 September 2009 16:10 UTC www.arraydev.com [Source type: FILTERED WITH BAYES]

^ The IP addresses of the root servers are well known to all name servers.
  • JIBC 22 September 2009 16:10 UTC www.arraydev.com [Source type: FILTERED WITH BAYES]

^ If you check IP addresses.
  • Infowars Under Sophisticated Denial of Service Attack 19 January 2010 18:018 UTC www.infowars.com [Source type: FILTERED WITH BAYES]

). To be more efficient and avoid affecting your network connectivity, it can be managed by your ISP.[32]
.Sinkholing routes to a valid IP address which analyzes traffic and reject bad ones.^ Having a separate emergency block of IP addresses for critical servers with a separate route can be invaluable.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ The cracker then sends UDP packets to the port 19 ( chargen ) to one of the "victims" spoofing the IP address and the source port from the other one.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ This route is a series of router IP addresses that the packets will have to follow.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

.Sinkholing is not efficient for most severe attacks.^ As a result, blocking the prefixes that correspond to the attack sources results in blocking most Internet prefixes, thereby causing severe collateral damage.
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

Clean pipes

.All traffic is passed through a "cleaning center" via a proxy, which separates "bad" traffic (DDoS and also other common internet attacks) and only sends good traffic beyond to the server.^ A DDoS attack is where a server is so flooded with meaningless traffic that it can’t do anything.
  • The Official DreamHost Blog! » Massive DDOS Attack 19 January 2010 18:018 UTC blog.dreamhost.com [Source type: General]

^ A DDoS attack involves sending large amounts of data that renders Web servers unusable by obstructing communication between the intended server and the target.
  • Urgent-Massive DDOS Attack! 12 September 2009 12:012 UTC forums.comodo.com [Source type: General]

^ A client establishes a privileged channel to a server through a capability exchange handshake; the client includes the capability in each subsequent packet it sends to the server; each router along the path verifies the capability and gives priority to privileged traffic.
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

.The provider needs central connectivity to the Internet to manage this kind of service.^ Attacks on wired networks do not require any NICs or external antennae, yet often do have the need of a (broadband) connection to the Internet.
  • Denial-of-service attack 11 September 2009 4:11 UTC exploits.net [Source type: FILTERED WITH BAYES]

^ Jack - August 6th, 2009 at 10:36 am PDT I agree that the internet is brilliantly designed to be decentralized but it seems humans are brilliantly designed to be customers to userfriendly centralized services.
  • Oooh Dramatic! Twitter Gets DDOSed 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

^ This is possible because the attack gateway is the border router providing Internet connectivity to the attack source.
  • Active Internet Traffic Filtering: Real-Time Response to Denial-of-Service Attacks 19 January 2010 18:018 UTC www-dsg.stanford.edu [Source type: FILTERED WITH BAYES]

[33]
.Prolexic and Verisign are examples of providers of this service.^ For example, the netmask service may be provided at the kernel level.
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]
  • The World Wide Web Security FAQ - Securing against Denial of Service attacks 19 January 2010 18:018 UTC www.windowsecurity.com [Source type: FILTERED WITH BAYES]

[34][35]

Side effects of DoS attacks

Backscatter

.In computer network security, backscatter is a side-effect of a spoofed denial of service (DoS) attack.^ Prevent Denial of Service (DOS) attacks in your web application .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]

^ Twitter victim of denial-of-service attack .
  • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

^ Twitter hit by denial of service attack .
  • Twitter: Ongoing denial-of-service attack - Blogrunner 19 January 2010 18:018 UTC www.blogrunner.com [Source type: News]

.In this kind of attack, the attacker spoofs (or forges) the source address in IP packets sent to the victim.^ The attacker spoofs the requests with the victim's address.
  • Protecting Electronic Commerce From DistributedDenial-of-Service Attacks 19 January 2010 18:018 UTC www2002.org [Source type: FILTERED WITH BAYES]

^ An example of such an attack is documented in [ 18 ], where the attacker spoofs the source address on a packet sent to the victim's UDP echo port.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ The replies are sent directly to the spoofed address of the attack destination.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

.In general, the victim machine can not distinguish between the spoofed packets and legitimate packets, so the victim responds to the spoofed packets as it normally would.^ An alternative DHCP-based attack is simply to respond faster than the legitimate DHCP server, and to give out an address that is not useful to the victim.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ The cracker then sends UDP packets to the port 19 ( chargen ) to one of the "victims" spoofing the IP address and the source port from the other one.
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ To implement an ARP Spoofing attack, the cracker will use an ARP packet generator such as ARPSpoof or nemesis .
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

These response packets are known as backscatter.
.If the attacker is spoofing source addresses randomly, the backscatter response packets from the victim will be sent back to random destinations.^ An example of such an attack is documented in [ 18 ], where the attacker spoofs the source address on a packet sent to the victim's UDP echo port.
  • RFC 4732 - Internet Denial-of-Service Considerations 11 September 2009 4:11 UTC tools.ietf.org [Source type: FILTERED WITH BAYES]

^ The replies are sent directly to the spoofed address of the attack destination.
  • Defeating DDoS 22 September 2009 16:10 UTC www10.org [Source type: FILTERED WITH BAYES]

^ The backscatter packets’ source address is that of the victim, but the packet’s destination address is randomly spoofed.
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

.This effect can be used by network telescopes as indirect evidence of such attacks.^ This attack does not work; it makes use of a postulated class of weak key pairs which has the S-box keys and eight successive round keys equal, but no such pairs exist.
  • Crypto-Gram: February 15, 2000 12 September 2009 12:012 UTC www.schneier.com [Source type: FILTERED WITH BAYES]

^ To implement an ARP Spoofing attack, the cracker will use an ARP packet generator such as ARPSpoof or nemesis .
  • lf282, SystemAdministration: External attacks 19 January 2010 18:018 UTC www.linuxfocus.org [Source type: Reference]

^ Always a WAYY too easy excuse, don’t believe that for a second…why is their network not protected against such attacks!?!?
  • DreamHost Status » Blog Archive » Major DNS DOS attack 19 January 2010 18:018 UTC www.dreamhoststatus.com [Source type: FILTERED WITH BAYES]

.The term "backscatter analysis" refers to observing backscatter packets arriving at a statistically significant portion of the IP address space to determine characteristics of DoS attacks and victims.^ DoS attacks on 5,000 distinct victims .
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

^ In the backscatter analysis project, 1 researchers monitored a wide IP address space for incoming unsolicited “backscatter” packets.
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

^ The backscatter packets’ source address is that of the victim, but the packet’s destination address is randomly spoofed.
  • Denial-of-Service Attack-Detection Techniques 19 January 2010 18:018 UTC dsonline.computer.org [Source type: Academic]

An educational animation describing such backscatter can be found on the animations page maintained by the Cooperative Association for Internet Data Analysis.

Denial-of-service attacks and the law

.In the Police and Justice Act 2006, the United Kingdom specifically outlawed denial-of-service attacks and set a maximum penalty of 10 years in prison.^ Update 7: It’s a denial of service attack .
  • Serious Twitter Outage Ongoing, Denial Of Service Attack (Updated) 19 January 2010 18:018 UTC www.techcrunch.com [Source type: General]

^ Securing against Denial of Service attacks .
  • WWW Security FAQ: Securing Against Denial of Service Attacks 19 January 2010 18:018 UTC www.w3.org [Source type: FILTERED WITH BAYES]

^ You have succeeded in Denial of Service Attack.” .
  • Prevent Denial of Service (DOS) attacks in your web application - Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5 19 January 2010 18:018 UTC msmvps.com [Source type: General]

[36]

See also

Notes and references

  1. ^ Yuval, Fledel. Uri, Kanonov. Yuval, Elovici. Shlomi, Dolev. Chanan, Glezer. "Google Android: A Comprehensive Security Assessment". IEEE Security & Privacy (IEEE) (in press). doi:10.1109/MSP.2010.2. ISSN 1540-7993. 
  2. ^ a b Phillip Boyle (2000). "SANS Institute - Intrusion Detection FAQ: Distributed Denial of Service Attack Tools: n/a". SANS Institute. http://www.sans.org/resources/idfaq/trinoo.php. Retrieved May 2, 2008. 
  3. ^ Mindi McDowell (2007). "Cyber Security Tip ST04-015". United States Computer Emergency Readiness Team. http://www.us-cert.gov/cas/tips/ST04-015.html. Retrieved May 2, 2008. 
  4. ^ "Types of DDoS Attacks". 2001. http://anml.iu.edu/ddos/types.html. Retrieved May 2, 2008. 
  5. ^ "CERT Advisory CA-1997-28 IP Denial-of-Service Attacks". CERT. 1998. http://www.cert.org/advisories/CA-1997-28.html. Retrieved May 2, 2008. 
  6. ^ Leyden, John (2008-05-21). "Phlashing attack thrashes embedded systems". theregister.co.uk. http://www.theregister.co.uk/2008/05/21/phlashing/. Retrieved 2009-03-07. 
  7. ^ "Permanent Denial-of-Service Attack Sabotages Hardware". Dark Reading. 2008. http://www.darkreading.com/document.asp?doc_id=154270&WT.svl=news1_1. Retrieved May 19, 2008. 
  8. ^ a b "EUSecWest Applied Security Conference: London, U.K.". EUSecWest. 2008. http://eusecwest.com/speakers.html#Smith. 
  9. ^ The "stacheldraht" distributed denial of service attack tool
  10. ^ US credit card firm fights DDoS attack
  11. ^ Paxson, Vern (2001), An Analysis of Using Reflectors for Distributed Denial-of-Service Attacks
  12. ^ Vaughn, Randal and Evron, Gadi (2006), DNS Amplification Attacks
  13. ^ Encyclopaedia Of Information Technology. Atlantic Publishers & Distributors. 2007. pp. 397. ISBN 8126907525. 
  14. ^ Schwabach, Aaron (2006). Internet and the Law. ABC-CLIO. pp. 325. ISBN 1851097317. 
  15. ^ Lu, Xicheng; Wei Zhao (2005). Networking and Mobile Computing. Birkhäuser. pp. 424. ISBN 3540281029. 
  16. ^ "YouTube sued by sound-alike site". BBC News. 2006-11-02. http://news.bbc.co.uk/2/hi/business/6108502.stm. 
  17. ^ "RFC 3552 - Guidelines for Writing RFC Text on Security Considerations". July 2003. http://www.faqs.org/rfcs/rfc3552.html. 
  18. ^ January 2001 thread on the UNISOG mailing list
  19. ^ Honeynet Project Reverse Challenge
  20. ^ "Factsheet - Root server attack on 6 February 2007". ICANN. 2007-03-01. http://www.icann.org/announcements/factsheet-dns-attack-08mar07.pdf. Retrieved 2009-08-01. 
  21. ^ "Before the Gunfire, Cyberattacks". http://www.nytimes.com/2008/08/13/technology/13cyber.html?em. Retrieved 2008-08-12. 
  22. ^ Shachtman, Noah (2009-06-15). "Activists Launch Hack Attacks on Tehran Regime". Wired. http://www.wired.com/dangerroom/2009/06/activists-launch-hack-attacks-on-tehran-regime/. Retrieved 2009-06-15. 
  23. ^ Outpouring of searches for the late Michael Jackson, 6/26/2009, Official Google Blog
  24. ^ Pirate Bay Hit With DDoS Attack After "Selling Out",8:01 AM - July 1, 2009, by Jane McEntegart - Tom's Hardware
  25. ^ Ongoing denial-of-service attack, 6th August 2009, Twitter Status Blog
  26. ^ Facebook Down. Twitter Down. Social Media Meltdown., 2009/08/06, By Pete Cashmore, Mashable
  27. ^ "Professor Main Target of Assault on Twitter", New York Times (8 August 2009) accessdate=2009-08-07
  28. ^ Managing WLAN Risks with Vulnerability Assessment, 2008/8/5, By Lisa Phifer:Core Competence, Inc. ,Technology Whitepaper, AirMagnet, Inc.
  29. ^ Tomasz Grabowski (2002). "User save yourself". http://obfusc.at/ed/ddos_eng.html. Retrieved 2009-02-02. 
  30. ^ OpenBSD's pf is a packet filter some providers use for exactly this purpose. [1]
  31. ^ "Some IoS tips for Internet Service (Providers)" (Mehmet Suzen)
  32. ^ Distributed Denial of Service Attacks, by Charalampos Patrikakis, Michalis Masikos, and Olga Zouraraki, The Internet Protocol Journal - Volume 7, Number 4, National Technical University of Athens, Cisco Systems Inc
  33. ^ "DDoS Mitigation via Regional Cleaning Centers (Jan 2004)"
  34. ^ "VeriSign Rolls Out DDoS Monitoring Service"
  35. ^ "DDoS: A Threat That's More Common Than You Think"
  36. ^ U.K. outlaws denial-of-service attacks, November 10, 2006, By Tom Espiner - CNET News

External links


Simple English

A Denial-of-Service attack (DoS) is when someone tries to stop someone else from viewing parts of the internet. People who have slower internet connections get more attacks.[1][2][3]

Types

There are different kinds of DoS attacks:

  • Flood attack - This is when a system gets too much internet traffic (people trying to connect to it). The traffic uses bandwidth and the internet servers slow down and eventually stop.[4]
  • Logic and software attacks - Internet packets are sent that are supposed to use bugs in the software or system. These attacks are easier to defend against because firewall or software patches usually correct the problem.[4]
  • Distributed Denial-of-Service attack - This type of attack uses either flood attacks or logic attacks, but it comes many different computers under the attacker's control (see Botnet). This type of attack is one of the most often used, and usually against company websites. This type of attack is often the hardest to prevent, track, and stop.[2][3]

History

In the 1990s and early 2000s, many web companies were hit by DoS attacks. For example, Microsoft was hit DoS attacks in early 2001. Many users were unable to access the Microsoft website.[2][3]

References


Citable sentences

Up to date as of December 19, 2010

Here are sentences from other pages on Denial-of-service attack, which are similar to those in the above article.








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