Thursday, January 05, 2006

WMF: How to uninstall the unofficial patch an install the official patch

SANS has released instructions on how to proceed if you are using the unoffical WMF patch.
Many of you already know this if you receive advance notification from Microsoft. For everybody else, see their announcement about an early release of the WMF patch. The patch and details about it are available here. If you have installed any of the earlier patches or workarounds, here is our recommendation for updating:

1. Reboot your system to clear any vulnerable files from memory
2. Download and apply the new patch
3. Reboot
4. Uninstall the unofficial patch, by using Add/Remove Programs on single systems. If you used msi to install the patch on multiple machines you can uninstall it with this:
msiexec.exe /X{E1CDC5B0-7AFB-11DA-8CD6-0800200C9A66} /qn
5. Re-register the .dll if you previously unregistered it (use the same command but without the "-u"):
regsvr32 %windir%\system32\shimgvw.dll
6. Reboot one more time just for good measure

We tested the patch, and it does block the attack just like the unofficial patch does.

If you experience any problems with the official patch, check and call the toll-free number listed for free assistance. Microsoft will not support the unofficial patch. As an alternative to the sequence shown above, you may want to uninstall the unofficial patch first. But make sure you keep shimgvw.dll unregistered until the official patch is applied. Either sequence works in our testing. Removing the unofficial patch later provides an extra layer of protection.

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