Windows 98 and the WMF exploit

I’ve seen breathless headlines that say “Windows PCs face ‘huge’ virus threat; Affects every MICROSOFT OS shipped since 1990…” and really would like to try to clarify (again) what the situation is. Yes, the bug or vulnerability that’s currently being exploited exists as far back as Windows 3.0, but as far as I can tell there is not an active, current exploit that is taking advantage of this flaw in earlier versions of windows. Currently the exploit only seems to affect Windows 2000, XP, and Vista.

This doesn’t mean that Windows 98 users should snicker and feel somehow vindicated for not upgrading. It may be that a variation of the exploit comes out tomorrow or the next day, or next week that actively exploits the bug in earlier Windows systems. I spent a good amount of time yesterday and now again this evening with a Windows 98 SE virtual machine (in QEMU) trying to see if I could get the exploit to work. I tried a number of samples found online and nothing seemed to gain traction. I then fired up metasploit and tried several variations on getting that to exploit the Windows 98 VM… I tried several different filename extensions, opening them in several included image viewers (mspaint as well). I tried simple payloads like just running c:\windows\calc.exe …. all that and nothing happened.

I suspect that for the exploit to work on pre Windows XP systems it may require third party software to make that happen. I have tested on a clean Windows 98 SE install. (Only a hex-editor has been added) It should be a default installation with no peculiar changes. I haven’t tried with Office installed. Maybe that would make a difference. There was mention of Lotus Notes bypassing the “unregister workaround” a few days back. Maybe that would prove a vulnerable combination. Just because I haven’t seen it happen doesn’t mean it’s not happening though.

I plan to leave comments open on this thread. I’d like to hear from anyone that’s seen this hit Windows 98 and if possible a short list of installed software. It’s worth noting that you can’t unregister the shimgvw.dll on Windows 98 as it’s not there…. the vulnerability itself apparently is in gdi32.dll, but shimgvw.dll has been the primary avenue.

–update 10:41PM EST–

I just took another look after reading a forum thread suggesting irfanView or another image viewer would be all it would take for Windows98 to be affected by the exploit. I used metasploit to setup an exploit that would run calc.exe and irfanView complained about a malformed header and didn’t open the file.

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