Over the last 24 hours, we've seen three different WMF files carrying the zero-day WMF exploit. We currently detect them as W32/PFV-Exploit .A, .B and .C.
Fellow researchers at Sunbelt have also blogged about this. They have discovered more sites that are carrying malicious WMF files. You might want to block these sites at your firewall while waiting for a Microsoft patch:
Crackz [dot] ws unionseek [dot] com www.tfcco [dot] com Iframeurl [dot] biz beehappyy [dot] biz
And funnily enough, according to WHOIS, domain beehappyy.biz is owned by a previous president of Soviet Union:
Do note that it's really easy to get burned by this exploit if you're analysing it under Windows. All you need to do is to access an infected web site with IE or view a folder with infected files with the Windows Explorer.
You can get burned even while working in a DOS box! This happened on one of our test machines where we simply used the WGET command-line tool to download a malicious WMF file. That's it, it was enough to download the file. So how on earth did it have a chance to execute?
The test machine had Google Desktop installed. It seems that Google Desktop creates an index of the metadata of all images too, and it issues an API call to the vulnerable Windows component SHIMGVW.DLL to extract this info. This is enough to invoke the exploit and infect the machine. This all happens in realtime as Google Desktop contains a file system filter and will index new files in realtime.
So, be careful out there. And disable indexing of media files (or get rid of Google Desktop) if you're handling infected files under Windows.