Microsoft patches critical top-to-bottom bugs in Windows

Microsoft Corp. today posted eight security updates -- more than half marked "critical" -- that patch 10 bugs in Windows, Office and Internet Explorer.

Of the 10 vulnerabilities plugged today, Microsoft labeled seven as critical, the highest rating in its four-step threat-scoring system. Of the remainder, two were pegged as "important" and one as merely "moderate."

Analysts agreed that the most serious vulnerabilities disclosed today were the two plugged by MS08-021, a critical update for every currently supported version of Windows, including the just-released Vista Service Pack 1 (SP1) and the even newer Windows Server 2008. "That's right across the board," said Tyler Reguly, a security research engineer at nCircle Network Security Inc.

"All versions of Windows are affected," echoed Amol Sarwate, manager of Qualys Inc.'s vulnerability research lab. "You don't need to have any special software on your PC to be vulnerable."

The MS08-021 update, said Microsoft in the advisory accompanying the release, fixes two flaws in Windows' GDI, or graphics device interface, one of the core components of the operating system. Attackers can use malformed WMF (Windows Metafile) or EMF (Enhanced Metafile) image files to trigger the bugs and "take complete control of an affected system," said Microsoft.

"Users who simply view an image online or in e-mail could be compromised," said Sarwate.

Both Sarwate and Reguly noted that there are similarities between the two new GDI vulnerabilities and ones revealed in late 2005, which were extensively used by attackers for months afterward. In fact, Microsoft patched that earlier GDI vulnerability -- which was also exploited by malicious WMF and EMF files -- "out-of-cycle," or outside of its normal second-Tuesday-of-the-month update schedule.

"They are similar in scope," said Sarwate. "A malformed image file can execute code on any version of Windows." He also said that he expects attackers to make use of the vulnerability, adding, "This is wormable."

Although MS08-021 was tops on both researchers' lists, Microsoft also issued critical updates for an Office-affiliated application called Project, as well as Internet Explorer, VBScript and Jscript. It also released a patch for an ActiveX control used by Windows' Help system.

The last -- labeled MS08-023 by Microsoft -- caught the attention of both researchers, not because it patches Microsoft's own ActiveX but because it also sets the "kill bit" for a third-party program, Yahoo Inc.'s Music Jukebox.

Both Reguly and Sarwate said that was a first for Microsoft. "They're setting kill bits for third-party applications, software that doesn't come with Windows," said Reguly. "I wonder if this means that they'll work with others in the future to make broader use of the Windows Update engine."