Like clockwork, Microsoft has posted the first Patch Day of the new year. In a word, I’d summarize it as average.
As they forewarned in their advanced notification last week, Microsoft released seven security bulletins today, which include six updates for Windows and one update for a Microsoft development tool (specifically an AntiXSS library). They only rate one of the Windows bulletins as Critical, but some of the Important bulletins also fix significant flaws that could allow attackers to execute code (though with more user interaction or difficulty).
One noteworthy aspect of today’s Patch Day is that two of the bulletins fix flaws within some Microsoft security mechanisms. One update fixes a flaw in SafeSEH, a Windows security mechanism that makes it more difficult for attackers to leverage buffer overflow or memory corruption flaws. Another bulletin fixes an information disclosure flaw in AntiXSS, a developer library that Microsoft offers to ASP.NET coders. AntiXSS is essentially an encoding library that helps web developers sanitize user input in their web applications. Sanitizing such input helps prevent your web application from suffering from cross-site scripting (XSS) vulnerabilities.
Though I find the security mechanism issues more interesting, the most severe bulletin in today’s batch corrects two serious issues in Windows’ media handling components. By enticing you to play maliciously crafted media, and attacker could exploit these issues to execute code on your computer, potentially gaining full control of it.
You can learn more about today’s updates in Microsoft’s January summary bulletin, which lists the bulletins from the most to least severe. Microsoft’s severity ratings seem right on to me, this month, so I recommend you apply the updates in that order. As is normally the case with Microsoft updates, you should probably test the patches before deploying them in your production network — especially ones that affect your production servers.
I’ll post a more detail, consolidated Windows alert here, shortly. However, I’ll probably not post a detailed alert about the AntiXSS update, since I suspect few of our readers and customers use it. That said, if you are a security minded ASP.NET developer that does leverage this library, you should definitely refer to Microsoft’s bulletin for its patch.
NOTE: Today is technically Adobe Patch Day as well, and they have released a security bulletin concerning Reader and Acrobat. We’ll post a more detailed alert about this Reader update too, but concerned Adobe users can download and install it now. Just refer to the Solution section of this bulletin. – Corey Nachreiner, CISSP