Microsoft rushes patches to fix 'big deal' programming flaw

Computerworld - As promised, Microsoft Corp. today patched six vulnerabilities in Internet Explorer and Visual Studio with the first "out-of-cycle" update since last October, when it plugged a hole that the Conficker worm later used to run rampant.

Microsoft has been working on the Visual Studio bugs, and coordinating with third-party developers who may have crafted vulnerable software using Visual Studio, since early 2008.

As some had speculated, Microsoft rushed the patches to users this week to preempt a presentation slated for tomorrow at Black Hat by several security researchers. The researchers plan to demonstrate a way for attackers to bypass the "kill-bit" defenses that Microsoft frequently deploys as a stop-gap measure for fixing bugs.

"We put this out of cycle because we have seen at least one attack using an ATL vulnerability," Mike Reavey, director of the Microsoft Security Response Center (MSRC), said in an interview today. "And there was more speculation and more details being released before Black Hat. We had the patches ready for broad release, so we decided to release them today."

Without the pressure from Black Hat, Microsoft would have waited until Aug. 11, when the company will issue its next regularly-scheduled security update.

The two emergency updates, MS09-034 and MS09-035, fixed three "critical" flaws in IE, added new defensive technology to the browser and patched three "moderate" bugs in Visual Studio.

But in an unusual reversal, Microsoft hinted -- and some researchers agreed -- that the moderate bugs might actually pose the more serious long-term threat. That's because the Visual Studio vulnerabilities are in a code "library," dubbed Active Template Library (ATL), that Microsoft and an unknown number of third-party developers used to create their own ActiveX controls and application components.

"ATL is a C++ library, and one that's pretty commonly used by developers," said Amol Sarwate, the manager of Qualys Inc.'s vulnerability research lab.

"This will be one of those where users are vulnerable from hackers much longer than the usual," added John Pescatore, an analyst at Gartner Inc. "This is a big deal. Microsoft may be fixing the underlying problem in ATL and pushing out this shielding thing that will protect users of IE, but there's no way of knowing how many applications or controls have this flaw baked into them."

"This is a complex issue, providing a comprehensive response to a library vulnerability," Reavey acknowledged. "Library issues are hard to deal with, and take a lot of collaboration to resolve them." That's because a library flaw affects not just the development platform -- in this case Visual Studio -- but can also creep into the resulting code written with that platform.