Viruses, spyware, and other junk can be installed on your computer through the WMF - Windows Meta Files that are viewed as vector graphics by various applications including Windows Fax Viewer. An example of a healthy WMF file is here.
The mechanism behind the bug is trivial: whenever a WMF fails to open, a code attached to the file is automatically executed. It is a rather important part of the WMF design which will make it harder for Microsoft to agree what it takes to fix the bug. Consider frequent updates of your antivirus software, antispyware software, and other recommendations listed here, including Ilfak Guilfanov's hotfix from hexblog.com.
Monday, January 2, 2006
WMF bug
A serious bug affecting all users of all types of the Windows operating system - and all internet browsers under Windows including MSIE and Firefox - remains unpatched.