Patch Tuesday: Time to use the Flame-retardant Windows Update client

When Patch Tuesday rolls around next week, Microsoft will address three critical security issues using an improved version of Windows Update that closes a loophole exploited by Flame malware.

That update to Windows Update has been distributed by Microsoft since the middle of last month but missed June's Patch Tuesday. The fix is important because it addresses the flaw that allowed Flame's authors to certify that malware they were sending to victim machines was authenticated by Microsoft, making the malware as trusted as an actual Windows security update.

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As for the July security bulletin being released next Tuesday, Microsoft says it is issuing nine security bulletins, three of them critical and designed to shore up vulnerabilities in Windows. One of them also affects Internet Explorer.

Each of the critical bulletins address flaws that if exploited could result in remote code execution on attacked machines. The browser vulnerability affects Internet Explorer 9, the latest version of the software.

Other platforms affected by the three critical updates are certain versions of Windows XP; Windows Server 2003, 2008 and 2008 R2; and Windows 7.

While Microsoft policy is not to reveal ahead of time what vulnerabilities are being addressed in its security bulletins, security experts have some idea what may be included.

"Bulletin 1, rated 'critical,' affects all versions of Windows, and we expect it to address the XML vulnerability disclosed by Microsoft in June's Patch Tuesday as KB2719615," says Wolfgang Kandek, CTO of Qualys Inc., in a blog. "This bulletin will be the highest priority for users, at least for those who did not apply Microsoft's FixIt supplied in the advisory."

KB2719615, a.k.a. CVE-2012-1889, has been used in the wild and is a vulnerability in Microsoft XML Core Services 3.0, 4.0, 5.0, and 6.0, Microsoft says. Marcus Carey, a security researcher at Rapid7, concurs that the bulletin may address this problem.

If victims access specially crafted Web pages using Internet Explorer, code on the page could execute malicious code remotely in the browser. Successful exploits could allow attackers to gain the same user rights as the logged-on user, Microsoft says.

Others are not so sure that KB2719615 will be addressed. Paul Henry, security and forensic analyst at Lumension, notes that it remains unclear if Microsoft will be issuing such a patch. "Microsoft normally includes details in their pre-release information if a Day Zero patch is included," Henry says. "However, in the July pre-release, no mention of the issue was included."

A second bulletin, also critical, is surprising, Kandek says, because it addresses an Internet Explorer issue out of phase with the usual bimonthly cycle. It affects Internet Explorer 9, so only machines with Vista or above operating systems might be affected, he says. The third critical bulletin is ranked such for XP, Vista and Windows 7 and is considered moderate for all other operating systems.

A third critical bulletin also represents the potential for exploits that fully compromise systems without user interaction. "These bulletins affect both business and consumer users of all modern versions of Microsoft Operating Systems," Carey says, "so they should be attention-grabbers."

While the remainder of the bulletins are ranked as important, Kandek calls attention to No. 4, which addresses a problem that can allow remote execution of code from any version of Office for Windows. Ratings drop from critical to important when the exploits involved require victims to open files in order for the attacks to be successful. But he says bulletins ranked important can fix problems that are just as dangerous to some users.

"We typically consider important bulletins for Office as almost the same severity level as critical," Kandek says. "After all, these document-based attack campaigns are usually quite successful in convincing at least a subset of end users to open the malicious document."

Tim Greene covers Microsoft for Network World and writes the Mostly Microsoft blog. Reach him at tgreene@nww.com and follow him on Twitter @Tim_Greene.

Read more about software in Network World's Software section.

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