This tool checks your computer for infection by specific, prevalent malicious software (including Blaster, Sasser, and Mydoom) and helps to remove the infection if it is found. Microsoft will release an updated version of this tool on the second Tuesday of each month.

The Microsoft Windows Malicious Software Removal Tool checks Windows Vista, Windows 7, Windows XP, Windows 2000, and Windows Server 2003 computers for and helps remove infections by specific, prevalent malicious software—including Blaster, Sasser, and Mydoom. When the detection and removal process is complete, the tool displays a report describing the outcome, including which, if any, malicious software was detected and removed. The tool creates a log file named mrt.log in the %WINDIR%\debug folder.

This tool is not a replacement for an anti-virus product. To help protect your computer, you should use an anti-virus product.

Microsoft will release an updated version of this tool on the second Tuesday of each month. New versions will be made available through this web page, Windows Update, and the Malicious Software Removal Tool Web site on Microsoft.com.

To have the newest versions automatically delivered and installed as soon as they are released, set the Automatic Updates feature to Automatic. The version of this tool delivered by Windows Update runs on your computer once a month, in the background. If an infection is found, the tool will display a status report the next time you start your computer. If you would like to run this tool more than once a month, run the version that is available from this Web page or use the version on the Malicious Software Removal Tool Web site.

Please review KB890830 for the list of malicious software that the current version of the tool is capable of removing as well as usage instructions. Also, please be aware that this tool reports anonymous information back to Microsoft in the event that an infection is found or an error is encountered. The above KB article contains information on how to disable this functionality and what specific information is sent to Microsoft.

It is strongly recommended that you review KB891716 before you consider deploying this tool in an enterprise environment.

The user must be an administrator to run this tool. This tool will not run on any version of Windows 98, Windows ME, or Windows NT 4.0.

Note that this download is now a multi-lingual tool. For all supported languages, the same tool will show the correct language depending on the language of the operating system.