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Mozilla Firefox disables Microsoft .NET and WPF addons

This morning, I was prompted by Firefox that it had disabled the .NET Framework Assistant and the Windows Presentation Foundation addons. The popup concluded with the message that these addons have been known to cause stability or security issues with Firefox.

This is very interesting with vendors taking a proactive approach with kill switch functionality with known security vulnerabilities. To Microsoft’s credit, they are letting Mozilla block the addon until users go and patch. According to http://blogs.technet.com/srd/archive/2009/10/12/ms09-054.aspx Firefox users are “safe” from beeing exploited via the security issue, after having KB974455 (the Cumulative Security Update for Internet Explorer) installed.

Here is Mozilla security blog entry announcing this block, which Mozilla is implementing using its blocking mechanism.

If you are one of those people who wish to get their hands dirty, you can nuke it with regedit.

For x86 machines, Go to the folder HKEY_LOCAL_MACHINE > SOFTWARE > Mozilla > Firefox > Extensions
For x64 machines, Go to the folder HKEY_LOCAL_MACHINE > SOFTWARE > Wow6432Node > Mozilla > Firefox > Extensions
Delete key name ‘{20a82645-c095-46ed-80e3-08825760534b}’
The plugin is hiding in C:\WINDOWS\Microsoft.NET\Framework\v3.5\Windows Presentation Foundation\NPWPF.dll (and C:\WINDOWS\Microsoft.NET\Framework\v4.0.20506\WPF\NPWPF.dll if you have the .NET 4.0 beta).
Remove HKEY_LOCAL_MACHINE\SOFTWARE\MozillaPlugins\@microsoft.com/WPF,version=3.5
And HKEY_LOCAL_MACHINE\SOFTWARE\MozillaPlugins\@microsoft.com/WPF, version=4.0 if you have the 4.0 beta
  • For x86 machines, Go to the folder HKEY_LOCAL_MACHINE > SOFTWARE > Mozilla > Firefox > Extensions
  • For x64 machines, Go to the folder HKEY_LOCAL_MACHINE > SOFTWARE > Wow6432Node > Mozilla > Firefox > Extensions
  • Delete key name ‘{20a82645-c095-46ed-80e3-08825760534b}’

The plugin is hiding in C:\WINDOWS\Microsoft.NET\Framework\v3.5\Windows Presentation Foundation\NPWPF.dll (and C:\WINDOWS\Microsoft.NET\Framework\v4.0.20506\WPF\NPWPF.dll if you have the .NET 4.0 beta).

  • Remove HKEY_LOCAL_MACHINE>SOFTWARE>MozillaPlugins>@microsoft.com>WPF,version=3.5
  • And HKEY_LOCAL_MACHINE>SOFTWARE>MozillaPlugins>@microsoft.com>WPF, version=4.0 if you have the 4.0 beta

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Author: Ajit Gaddam

Ajit Gaddam is an accomplished technology executive and is currently the Head of Security Engineering at Visa, where he is responsible for building large scale AI driven cybersecurity products, leading engineering programs, and providing expert guidance on cybersecurity matters. He has presented at conferences worldwide, including USENIX Enigma, RSA, Black Hat, Strata Data Hadoop, COSO Dublin, and GCS Ukraine. Ajit has been quoted by major media organizations and his work has been showcased in academic journals, security publications, and in two published books. He is an active participant in various open source and standards bodies, is a prolific inventor of disruptive technologies (over 100+ global patents), and moonlights as an instructor (SANS, community colleges).

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