Microsoft patches zero-day Windows Media flaw

The software maker originally planned to release only six security bulletins as part of its monthly patch cycle. However, it added a seventh to deliver a fix for two flaws that affect the Windows Media Format, including one zero-day bug, a company representative said in a statement.

Microsoft also provided a patch for a zero-day vulnerability that affects Visual Studio 2005 developer tools. This security hole was disclosed last month and, contrary to the Windows Media issue, has already been used in cyberattacks, the company said.

However, there were no fixes Tuesday for a pair of known flaws in Microsoft Word that are also being exploited in malicious software.

"While we see Microsoft making an attempt to patch zero-day vulnerabilities, they are still struggling to keep up with the continuous influx of zero-day attacks," said Amol Sarwate, a research manager at vulnerability management company Qualys. "Microsoft is making a genuine effort. However, users are still exposed to attacks via the unpatched Word vulnerabilities."

Particulars of patches
The Windows Media issues are addressed in bulletin MS06-078, one of three "critical" security updates published by Microsoft on this "Patch Tuesday." The other high-risk vulnerabilities lie in Internet Explorer and in Visual Studio 2005.

Somebody could exploit the Windows Media flaws by tricking a user into opening a rigged media file or stream, Microsoft said. "An attacker who successfully exploited this vulnerability could take complete control of an affected system," it said.

Four vulnerabilities in Internet Explorer expose Windows PCs to a similar risk. Somebody could exploit the holes in the Web browser creating a malicious Web site, Microsoft said. None of the IE flaws had been previously disclosed, it said.

Deemed less serious by Microsoft are problems that affect the Windows Simple Network Management Protocol service, the Windows Client-Server Run-time Subsystem and the Windows Remote Installation Services, the company said. These were all rated "important"--one notch less serious than Microsoft's highest rating of "critical."

A vulnerability in the Outlook Express mail client was also tagged as "important."

Though Microsoft rates the SNMP flaw "important," it should still be considered very serious for business users, said Gunter Ollmann, director of IBM Internet Security Systems' X-Force unit.

"Although SNMP is not a default service, it is the de facto standard for monitoring critical business assets," Ollmann said in an e-mailed statement. "Because SNMP uses user datagram protocol, which doesn't require a handshake, internal attackers can spoof an identity and gain complete control of the network."

Microsoft offers a summary of its patches on its Web site. The fixes will be delivered via Automatic Updates in Windows and are available on Microsoft's Web site.