For the moment, there's little cause for alarm, added the SANS Internet Storm Center, which has been monitoring port 3372. "At this point, we see only little activity at port 3372, likely due to the fact that this PoC exploit does not actually execute any 'useful' code," wrote Johannes Ullrich, chief research officer at the ISC, in a note posted on the site.
Also out and about is proof-of-concept code that attacks a second, and newer vulnerability. A researcher from India has posted code that can bring a Windows system to a screeching halt by making IE consume 100 percent of the processor's cycles. On Tuesday, FrSIRT also ranked its alert on this new problem as "Critical."
The exploit leverages a vulnerability in Windows' rendering of WMF and EMF (Windows Metafile and Enhanced Metafile, respectively) images that was disclosed and patched Nov. 8.
Of the three security bulletins released by Microsoft this month, MS05-053, which patches the Metafile bug, was considered the most serious by security experts, even though some dismissed the idea of a major attack. "I think it's doubtful that we'll see this widely exploited," said Neel Mehta, the team leader for Internet Security Systems' (ISS) X-Force research group, at the time.
As with the other bug, Microsoft said that the result of a successful attack "could lead to a denial of service attack and not remote code execution."
Microsoft reminded users that the October and November updates protect against both possible exploits. "[We are] actively monitoring this situation to keep customers informed and to provide customer guidance as necessary," said Microsoft's Gunderson.