IE's VML (Vector Markup Language) vulnerability

A loose affiliation of security researchers going by the name of ZERT (Zeroday Emergency Response Team) has released a patch for the VML (Vector Markup Language) vulnerability, which increasingly is being exploited by criminals in malware attacks.

Microsoft is scheduled to fix the bug on October 10, the date it has set to release its monthly batch of security updates, but the company is under increasing pressure to release an earlier, "out-of-cycle" patch. The SANS Internet Storm Center today raised its alert level from green to yellow, an indication that attacks are becoming more widespread.

Microsoft's Solutions

Microsoft has suggested a number of workarounds to the problem, and the software vendor does not recommend that users install the new ZERT patch.

"We think it's great that there are people out there working to help protect our customers. But as we've always said, we cannot endorse third party updates," wrote Microsoft Security Response center operations manager Scott Deacon in a blog posting today.

Microsoft rigorously tests its patches to try to cut off any problems that the new software might introduce. The ZERT patch has not been widely tested and could introduce new problems when installed, security experts warn.

ZERT's Actions

ZERT plans to continue to release its own patches when particularly critical unpatched flaws begin to pose a "serious risk to the public, the infrastructure of the Internet or both," the group claims in a manifesto, published on its Web site.

"The purpose of ZERT is not to 'crack' products, but rather to 'uncrack' them by averting security vulnerabilities in them before they can be widely exploited," the group says.

ZERT sprang out of discussions on e-mail lists set up a few years ago by security researcher Gadi Evron, said ZERT member Randy Abrams, director of technical education with Eset in San Diego.

"Microsoft wants to assign a monthly patch and we understand that," said ZERT member Roger Thompson, who is chief technology officer with Atlanta's Exploit Prevention Labs. "There's a certain benefit of staying on the monthly patch, but when things start to pop, as we think this VML thing is, there's a need to do something."

The group's formation was spurred by Microsoft's WMF (Windows Metafile) vulnerability, which emerged in late 2005. Tens of thousands of Microsoft users downloaded third-party patches to fix that bug and Microsoft was eventually forced to release an out-of-cycle patch to address the problem.

"This has been the first real vulnerability [since then] that the members have felt can be patched fairly quickly," Abrams said.

Microsoft clearly does not want its users to get into the habit of installing third-party security patches, so if the ZERT software is widely downloaded, Microsoft may move more quickly with its own VML patch, Abrams said.