WMF 0-day update

Last night while I was in the midst of infecting a virtual machine, Microsoft issued a release that there’s a “possible vulnerability”… fortunately, their technical document is a bit more straightforward… technet advisory here. Spyware Confidential also has a good roundup on the coverage so far. There’s a bit more disturbing stuff coming too…

The Security Fix is reporting that this affects more than just Windows XP and WIndows 2003… in fact it affects every version of Windows back to Windows 98. Additionally, it affects any image that relies on the WMF viewer library, which unfortunately extends BEYOND WMF files. Even specially crafted JPG’s and GIF’s appear to be possible culprits.

The upshot of all of this is the “vectors” to exploit this are many: specially crafted image file in a web page; html email; (even email attachment); embedded image in a document, etc. The first workaround is sounding to be the best (if inelegant), becuase it disables the use of the vulnerable library.

That first workaround was…

Start button on the taskbar.
2. Click on Run…
3. Type “regsvr32 /u shimgvw.dll” to disable.
4. Click ok when the change dialog appears.

iDefense notes that this workaround may interfere with certain thumbnail images loading correctly, though I have used the hack on my machine and haven’t had any problems yet. The company notes that once Microsoft issues a patch, the WMF feature may be enabled again by entering the command “regsvr32 shimgvw.dll” in step three above.

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