Computer Security Wiki
Windows Defender

Windows Defender icon

Windows Defender screenshot
Windows Defender running under Windows Vista

Developed by


Latest Release

1.1.1593 (XP) 1.1.1600 (Vista) / September 16, 2008


Microsoft Windows

Type Antispyware software
License Proprietary software
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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 it is available as a free download for Windows XP and Windows Server 2003.


  1. 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.
  2. It also includes the ability to easily remove ActiveX applications that are installed.
  3. 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.

4. 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.

5. This implementation is similar to the real-time scanners of many anti-virus products on the market. Although not combined with Firefox, Windows Defender still scans downloaded files for malicious code.

6. The Advanced Tools section allows users to discover potential vulnerabilities with a series of Software Explorers.

7. They provide views of startup programs, currently running software, network connected applications, and Winsock providers (Winsock LSPs).

8. In each Explorer, every element is rated as either "Known", "Unknown" or "Potentially Unwanted".

9. 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.

10. 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).

11.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.


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