How To Remove Microsoft .NET Spyware Extension

Back around the end of January there was a Microsoft Windows Update (KB951847) that installed the SpyWare (done without user consent/knowledge and can not be removed easily) Microsoft .NET Framework Assistant 1.0 extension into Firefox. Note: If you have not install Windows Update KB951847 OR not using Windows Update this extension will not be installed.


Notice how the ‘Uninstall’ button is greyed out? I learned about this from a post )Microsoft Infiltrates Firefox) at GoFirefox! However, because I am using Shiretoko 3.1b3pre and the add-on was not compatible with this build it never fully installed. I was able to remove the add-on following these directions:

  1. Close Firefox
  2. In Windows Explorer go to this location:
    C:\WINDOWS\Microsoft.NET\Framework\v3.5\Windows Presentation Foundation\DotNetAssistantExtension
  3. This folder should contain 2 sub-folder and 2 files. Just in case for some odd reason you might need these files, create a zip or rar file containing these items and place it somewhere else.
  4. Delete everything in this folder, but leave the folder
  5. Restart Firefox and go to your add-ons list. The add-on should no longer be listed.
  6. In the address bar type about:config
  7. In the Filter field type general.useragent
  8. Look for an entry called general.useragent.extra.microsoftdotnet
  9. Right -click on the entry and select ‘reset’

Now, for the most part these steps worked for me. However, as I had mentioned earlier it never fully installed since it was not compatible with Shiretoko 3.1b3pre. In this case I completed Steps 1-5 but noticed the add-on was still there and still disabled. Next, I had to close Firefox again, go to my profile folder and remove the files: extensions.cache, extensions.ini and extensions.rdf. This forces Firefox to rebuild the extensions list, however when I did this step, the Night Tester Tools add-on broke. Not good, now about half my extensions that I had “forced” to work, weren’t working now. So I had to uninstall the Night Tester Tools extension, restart Firefox, re-install the extension, restart Firefox, over-ride compatibility on the currently disabled add-ons and restart Firefox once again. Since the ad-on never fully installed, I did not have an about:config entry for general.useragent.extra.microsoftdotnet

Updated 02/10/09: Added links for information about the KB951847 update and the Microsoft .NET Framework Assistant 1.0

Source: Dediomedo