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Microsoft patches critical Windows zero-day bug that hackers are now exploiting

Fixes first security flaw in Windows 8 Consumer Preview

April 10, 2012 04:20 PM ET

Computerworld - Microsoft today delivered six security updates to patch 11 vulnerabilities in Windows, Internet Explorer (IE), Office and several other products, including one bug that attackers are already exploiting.

The company also issued the first patch for Windows 8 Consumer Preview, the beta-like build Microsoft released at the end of February.

But it was MS12-027 that got the most attention today.

"Things got a bit more interesting today," said Andrew Storms, director of security operations at nCircle Security, "because Microsoft is reporting limited attacks in the wild."

Flaws that attackers exploit before a patch is available are called "zero-day" vulnerabilities.

The single vulnerability patched in MS12-027 is in an ActiveX control included with every 32-bit version of Office 2003, 2007 and 2010; Microsoft also called out SQL Server, Commerce Server, BizTalk Server, Visual FoxPro and Visual Basic as needing the patch.

Storms, other security experts and Microsoft, too, all identified MS12-027 as the first update users should install.

Hackers are already using the vulnerability in malformed text documents, which when opened either in Word or WordPad -- the latter is a bare bones text editor bundled with every version of Windows, including Windows 7 -- can hijack a PC, Microsoft acknowledged in a post to its Security Research & Defense (SRD) blog today.

"We list MS12-027 as our highest priority security update to deploy this month because we are aware of very limited, targeted attacks taking advantage of [the] CVE-2012-0158 vulnerability using specially-crafted Office documents," said Elia Florio, an engineer with the Microsoft Security Response Center, in the SRD blog post.

Microsoft did not disclose when it first became aware of the attacks, or who reported the vulnerability to its security team.

Storms speculated that an individual or company had been attacked, uncovered the bug and notified Microsoft.

Microsoft rarely deploys a patch "out of cycle," meaning outside its usual second Tuesday of every month schedule. The last such update was shipped in December 2011, and was the first for that year.

Also affected is software written by third-party developers who have bundled the buggy ActiveX control with their code or called it. Those developers will have to provide their own updates to customers.

"Any developer that has released an ActiveX control should review the information for this security bulletin," said Jason Miller, manager of research and development at VMware. "These developers may need to release updates to their own software to ensure they are not using a vulnerable file in their ActiveX control."

Attackers can also exploit this bug using "drive-by download" attacks that automatically trigger the vulnerability when IE users browse to a malicious site, Microsoft admitted.



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