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MS squashes 0day bug in July Patch Tuesday

Patches under-attack XML Core Services flaw in Flame-proof update

Microsoft has patched an under-attack zero-day vulnerability in XML Core Services as part of the July edition of Patch Tuesday.

The critical security update (MS12-043) addresses a security flaw that has made its way into the Blackhole Exploit toolkit since its discovery last month. A further two critical updates cover a cumulative security update for Internet Explorer and a remote code execution flaw in MS Data Access Components (a part of Windows), respectively. The six other bulletin issued on Tuesday cover lesser security flaws.

Andrew Storms, director of security operations for nCircle, noted that only under-attack versions of XML Core Services have been patched, as yet.

“The most important patch this month is undoubtedly the XML core services bug," Storms commented. "Microsoft issued an advisory for this bug in early June and we've already seen the exploit in a number of exploit toolkits and attacks have been reported in the wild."

"[The] XML version 5 patch for the bug isn't shipping today. The fix for this version is probably not ready yet, so Microsoft decided to deliver the other patches. So far, all the attacks in the wild utilize XML version 3, so this release, even though not totally complete, seems like a no-brainer."

Storms added that the IE patch is significant because it represents a step up in frequency for browser security updates from Microsoft.

"Usually, Microsoft sticks to an extensive two-month test cycle for Internet Explorer, so that's why we've only seen them every other month," he said.

"[An] MSRC post says that additional resources have been added to IE testing to reduce the test period. It's good to know that Microsoft can deliver IE patches faster, but IT security teams are probably less than thrilled, since they are going to see a lot more IE patches, including the one released today.”

Microsoft's summary of its security bulletins is here. The Internet Storm Centre has published an easier to understand overview here.

The July edition of Patch Tuesday marks the first time Microsoft has made use of an update mechanism that it hardened in response to an investigation into the Flame malware, a cyber-espionage tool that abused certain aspects of Redmond's update mechanism in order to spread. The investigation into Flame also resulted in Microsoft's decision to revoke 28 digital certificates, as a precaution.

In an advisory, Microsoft explains that the revoked certificates were vulnerable to spoofing attacks, hence the decision to replace them with something stronger. "Upon a routine review, we are placing these certificates in the Untrusted Certificate Store, and replacing them with new certificate authorities that meet our high standard of public-key infrastructure (PKI) management. We are unaware of any misuse of the certificate authorities, but are taking pre-emptive action to protect customers. This issue affects all supported releases of Microsoft Windows." ®

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