Microsoft Patches Won't Fix IE Zero-Day Vulnerability

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For many tech professionals, Tuesday will be all about the Consumer Electronics Show (CES) spectacle. For IT admins, though, the day is likely to be spent deploying Microsoft's first security patches of 2013. The collection of seven patches will address 12 problems, two of which have been classified as critical vulnerabilities. It won't, however, offer a permanent solution for an Internet Explorer (IE) vulnerability discovered in late December.

Both of the critical vulnerabilities Microsoft will patch allow attackers to remotely execute code on unpatched machines. One affects only Windows 7 and Windows Server 2008 R2 -- but the confined risk doesn't mitigate the potential damage, given that Windows 7 is the world's most widely deployed OS. The other involves virtually all Windows variations currently used in the enterprise: Windows XP through Windows 8, as well as Windows Server 2003, 2008, 2008 R2 and 2012. Instituting the patches could cause admins a few minor headaches; all but one of the seven patches, including the two most urgent ones, require that machines be restarted.

The presently unpatched zero-day vulnerability in IE, meanwhile, was first described by cybersecurity firm FireEye, which published a blog post on December 28, one day after receiving reports that the website for the Council on Foreign Relations had been compromised. FireEye said the site had been injected with malicious code due to an error in IE 8. The firm declined to provide in-depth technical details until Microsoft issues a solution, but it noted that the JavaScript involved includes a few peculiarities, such as exploiting only browsers whose OS language is English, Chinese, Japanese, Korean or Russian.

Microsoft acknowledged the problem a day later and revealed that IE 6, 7 and 8 are affected. The company explained that an attacker "could take complete control of an affected system" and has offered a workaround until a complete patch is released.

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Given how recently the exploit was discovered, it would have been surprising if Microsoft had bundled a patch into the forthcoming updates. The fact the IE 9 and 10 are not vulnerable takes a bit of the urgency off, but security firm Exodus Intelligence claims that the current workaround is easily subverted. The company provided technical details of the bypass to its customers, but will not make the information public until Microsoft has issued a patch.

In an earlier analysis, Exodus Intelligence co-founder Peter Vreugdenhil wrote that the vulnerability is "just another Internet Explorer use-after-free bug which was actually relatively easy to analyze and exploit." A Sophos Security blog post, meanwhile, took a more somewhat more aggressive tone in describing the risk, tracing the exploit to a handful of additional attacks and recommending that users avoid affected versions of IE.

In an email, IDC analyst Al Hilwa wrote that, "Releasing information about a vulnerability before it is patched is always a balancing act." If Microsoft learned that the exploit had become known within the hacker community, he asserted, the knowledge would compelled the the company's leaders to "exposite it and give recommendations even prior to figuring out a solution."