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Microsoft to patch unhackable Windows 7 bug later today

Continues 'defense-in-depth' practice by patching flaw in Vista, Windows 7, Server 2008

April 13, 2010 06:53 AM ET

Computerworld - Later today, Microsoft will play it safe by patching a Windows 7 bug that it says can't be exploited.

Of the 11 security bulletins that will be released in a few hours, Bulletin 7 will address one or more vulnerabilities in Windows 2000, Windows XP and Windows Server 2003.

But Microsoft will also offer the same update to users running Windows Vista, Windows 7 and Windows Server 2008, even though the company maintained last week that they were impervious to attack.

"Windows 7 users will be offered Bulletin 7 as a defense-in-depth update even though the [advanced notification] states that the issue does not affect Windows 7," said Jerry Bryant, a group manager with the Microsoft Security Response Center, in one of several e-mails replying to questions. "This means that the vulnerable code is in the software, but due to the improved protections built into Windows 7, there are no known vectors to reach it."

In other words, the vulnerability is there -- in Vista, Windows 7 and Server 2008 -- but Microsoft doesn't know how it could be exploited.

Better safe than sorry, security experts said.

"Absolutely, it's a good practice to fix these bugs," said Andrew Storms, director of security operations at nCircle Network Security. "Just a year ago, DEP [data execution prevention] and ASLR [address space layout randomization] were mitigating nearly every vulnerability for Internet Explorer on Vista. Yet we are seeing a steady rise in more researchers' finding and taking advantage of DEP bypass methods. And if DEP bypass continues to happen more often, then we'll be happy that Microsoft issued these fixes."

Wolfgang Kandek, chief technology officer at security risk and compliance management provider Qualys, not only agreed, but cited DEP and ASLR circumventions as well. "Installing the update for Windows 7, Server 2008 and Vista is definitely a recommended, and preemptive, action," he said. "We have seen cases in the past where attackers were able to string together multiple vulnerabilities to reach their goal, most recently at CanSecWest, where Peter Vreugdenhil used two bypasses to first get by ASLR, then DEP when he exploited IE8."

For his exploit expertise, Vreugdenhil, a Dutch freelance researcher, last month won $10,000 during the Pwn2Own hacking contest. His one-two punch was called "particularly impressive" by the contest organizer because it sidestepped DEP and ASLR, two cornerstones of Vista's and Windows 7's security.

Microsoft has patched untouchable vulnerabilities before, Bryant confirmed, citing several examples, including MS09-032, a July 2009 update that disabled a company-made ActiveX control said to be unexploitable in Vista or Server 2008. Prior to that, Microsoft issued MS09-015 (April 2009) and MS08-062 (October 2008) for similar defense-in-depth reasons.

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