Just when mass-mailer worms are becoming an endemic but utterly preventable problem, a whole new wrinkle is developing. Mass-mailer worms based on the Microsoft GDI+ vulnerability will probably slip through most perimeter e-mail protection facilities.
There is a client-side patch for Windows prior to XP Service Pack 2, which itself is not vulnerable, and there is some measure of imperfect protection for third-party programs. The third-party issue is probably not so bad in the short term, but the long term isnt pretty.
But the prospect of HTML e-mails—which, though they have no explicit attachments, infect the system and run arbitrary code on them—is extremely troubling to me. Numerous proof-of-concept exploits are appearing and, while I hear at least some of them do not reliably exploit the hole, its just a matter of time before one comes out that is troublesome enough.
Even though the patch is out there and SP2 users are basically safe, its hard to feel optimistic. Look at the last great worm, which I figure to be Sasser and its lesser imitations. This was a worm that could be blocked with a patch or at the firewall, and still it caused havoc. Theres less that can be done on an administrative basis to stop the coming JPEG worm.
But of the administrative possibilities for stopping this worm, the only practical one is to apply the patch. What else can be done? Disable HTML e-mail? Not practical anymore. Have the anti-virus engine scan JPEG files for the problem? Not practical—the performance hit would be atrocious. There really isnt a good workaround for corporate or home users. The truth of the situation is patch or die.
As I pointed out earlier, the problem of third-party programs that redistribute vulnerable copies of the GDIPLUS.DLL file is a difficult one, but I just dont see it as having the destructive potential of the browser/e-mail side of the problem.