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Windows Defender
Windows Defender icon.png
Windows Defender in Windows 7
Developer(s) Microsoft
Stable release 1.1.1593 (Windows XP and Windows Server 2003), 1.1.1600 (Windows Vista), 6.1.7600.0 (Windows 7)
Operating system Microsoft Windows
Available in English
Type Spyware removal software
License Proprietary software
Website Windows Defender website

Windows Defender, formerly known as Microsoft AntiSpyware, is a software product from Microsoft to prevent, remove and quarantine spyware in Microsoft Windows. It is included and enabled by default in Windows Vista and Windows 7, and is available as a free download for Windows XP and Windows Server 2003.


Basic features

Windows Defender features system scan capabilities similar to other free products on the market, and includes a number of real-time security agents that monitor several common areas of Windows for changes which may be caused by spyware. It also includes the ability to easily remove ActiveX applications that are installed. Also integrated is support for Microsoft's SpyNet network that allows users to report to Microsoft what they consider to be spyware, and what applications and device drivers they allow to be installed on their system.



Beta 1

Microsoft AntiSpyware Beta 1 (Version 1.0.701)

Windows Defender is based on GIANT AntiSpyware, which was originally developed by GIANT Company Software, Inc. The company's acquisition was announced by Microsoft on 16 December 2004.[1][2] While the original GIANT AntiSpyware supported older Windows versions, support for the Windows 9x line of operating systems was later dropped.

The first release of Microsoft AntiSpyware was released in beta form on 6 January 2005 and was basically a repackaged GIANT AntiSpyware.[1] It was then a free product (though only for genuine installations of Windows), contained few new features and was simply rebranded as a Microsoft product. More builds were released as 2005 progressed, with the last Beta 1 refresh released on 21 November 2005.

Beta 2

At the 2005 RSA Security conference, Chief Software Architect and co-founder of Microsoft, Bill Gates, announced that Windows Defender (which was known as Microsoft AntiSpyware prior to 4 November 2005) would be made available free of charge to all validly licensed Windows 2000, Windows XP, and Windows Server 2003 users to help secure their systems against the increasing malware threat.[3]

Windows Defender (Beta 2) was released on 13 February 2006. It featured the program's new name and a significant user interface redesign. The core engine was rewritten in C++, unlike the original GIANT-developed one, which was written in Visual Basic.[4] This improved the application's performance. Also, since beta 2, the program works as a Windows service, unlike earlier releases, which enables the application to protect the computer even when a user is not logged on. The Windows Defender application is technically an interface to the service, which also has the same name. Beta 2 also requires Windows Genuine Advantage validation. However, Windows Defender (Beta 2) did not contain some of the tools found in Microsoft AntiSpyware (Beta 1). Microsoft removed the System Inoculation, Secure Shredder and System Explorer tools found in MSAS (Beta 1) as well as the Tracks Eraser tool, which allowed users to easily delete many different types of temporary files related to Internet Explorer 6, including cookies, temporary internet files, and Windows Media Player playback history.[1] Microsoft later released German and Japanese versions of Windows Defender (Beta 2).

Final release

On 24 October 2006, Microsoft released the final version.[5] It supports Windows XP, Windows Server 2003 and Windows Vista; however, unlike the betas, it does not run on Windows 2000 by default.[6]


On 1 September 2009, Microsoft released Microsoft Security Essentials, a freeware anti-malware product. A Microsoft official notice posted earlier on 23 June 2009 on Microsoft community forum indicates that Microsoft Security Essentials supersedes Windows Defender as it covers a broader range of malware.[7] The same notice states that although users do not need to run Windows Defender anymore, both applications can remain installed side-by-side and later releases of Microsoft Security Essentials are expected to disable Windows Defender.[7]

Advanced features

Windows Defender is shown here blocking Hotbar, a known adware bundler.

Real-time protection

In the Windows Defender options, the user can configure real-time protection options:

  • Auto Start - Monitors lists of programs that are allowed to automatically run when the user starts the computer
  • System Configuration (settings) - Monitors security-related settings in Windows
  • Internet Explorer Add-ons - Monitors programs that automatically run when the user starts Internet Explorer
  • Internet Explorer Configurations (settings) - Monitors browser security settings
  • Internet Explorer Downloads - Monitors files and programs that are designed to work with Internet Explorer
  • Services and Drivers - Monitors services and drivers as they interact with Windows and programs
  • Application Execution - Monitors when programs start and any operations they perform while running
  • Application Registration - Monitors tools and files in the operating system where programs can register to run at any time
  • Windows Add-ons - Monitors add-on programs (also known as software utilities) for Windows

Internet Explorer integration

There is integration with Internet Explorer which enables files to be scanned when they are downloaded to help ensure that one does not accidentally download malicious software. This implementation is similar to the real-time scanners of many anti-virus products on the market. Although not combined with Firefox or other browsers, Windows Defender still scans downloaded files for malicious code, as part of the real-time protection.

Software Explorer

The Advanced Tools section allows users to discover potential vulnerabilities with a series of Software Explorers. They provide views of startup programs, currently running software, network connected applications, and Winsock providers (Winsock LSPs). In each Explorer, every element is rated as either "Known", "Unknown" or "Potentially Unwanted". The first and last categories carry a link to learn more about the particular item, and the second category invites users to submit the program to SpyNet for analysis by experts.

Windows Vista-specific functionality

Windows Defender in Windows Vista automatically blocks all startup items that require administrator privileges to run (this is considered suspicious behavior for a startup item). This automatic blocking is related to the UAC (User Account Control) functionality in Windows Vista, and requires users to manually run each of these startup items each time they log in.

See also


  1. ^ a b c Thurrot, Paul (20 December 2004). "Microsoft Windows Anti-Spyware Preview: Paul Thurott's SuperSite for Windows". SuperSite for Windows. Retrieved 8 October 2009.  
  2. ^ "Microsoft Acquires Anti-Spyware Leader GIANT Company". PressPass. Microsoft Corporation. December 16, 2004. Retrieved 11 November 2009.  
  3. ^ "Gates Highlights Progress on Security, Outlines Next Steps for Continued Innovation". PressPass. Microsoft Corporation. February 15, 2005. Retrieved 11 November 2009.  
  4. ^ Thurrott, Paul (14 February 2006). "Windows Defender Beta 2 Review: Paul Thurrott's SuperSite for Windows". SuperSite for Windows. Retrieved 8 October 2009.  
  5. ^ Thurrott, Paul (24 October 2006). "Finally, Microsoft Ships Windows Defender". Windows IT Pro. Retrieved 25 October 2006.  
  6. ^ "Windows Defender: Support → FAQ". Microsoft Corporation. Retrieved 8 October 2009. "Q: What are the system requirements for Windows Defender? A: System requirements: [...] Note: Windows Defender does not run on the Microsoft Windows 2000."  
  7. ^ a b Hau, Kevin (23 June 2009). "Windows Defender and Microsoft Security Essentials". Microsoft Corporation. Retrieved 8 October 2009.  

External links

Simple English

Windows Defender, which used to be called Microsoft AntiSpyware, is a application made by Microsoft.


Windows Defende was released on October 24, 2006.

Windows Defender prevents, removes and quarantine's spyware in Microsoft Windows.

It is included in Windows Vista and Windows 7 and can be downloaded for free if you own Windows XP or Windows Server 2003.

Other pages

Other websites


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