One of the forthcoming patches will close the last remaining vulnerability being exploited by Stuxnet. According to a blog post by Mike Reavey, director of Microsoft Security Response Center, "this is a local elevation of privilege vulnerability and we've seen no evidence of its use in active exploits aside from the Stuxnet malware."
Microsoft is also patching a bug in IE that's currently being exploited by attackers, though Reavey rates the number of related exploits as being "pretty low," and notes that "customers running Internet Explorer 8 remained protected by default due to the extra protection provided by Data Execution Prevention (DEP)."
Expect enterprises to punt many of these patches until 2011. "The high number of advisories will present a challenge to all Windows system administrators, especially with the holidays shortening the available working hours," said Wolfgang Kandek, CTO of Qualys.
December's Patch Tuesday brings the total number of security bulletins Microsoft released in 2010 to 106 -- the highest number yet. "This isn't really surprising when you think about product lifecycles and the nature of vulnerability research," said Reavey, highlighting both the fact that Microsoft supports products for 10 years, as well as ongoing improvements in vulnerability research, meaning that researchers are finding more bugs. On that note, he said that 80% of Microsoft product vulnerabilities are "reported to us cooperatively," meaning that Microsoft has a heads-up before knowledge of the bug goes public.
One new bug, however, won't make the count. On Thursday, IT security research firm Vupen disclosed a new, zero-day vulnerability in Internet Explorer 6, 7, and 8. Vupen rates the vulnerability as critical, because attackers could use it to comprise a system. According to its security advisory, the issue stems from "a use-after-free error within the 'mshtml.dll' library when processing a web page referencing a CSS (cascading style sheets) file that includes various '@import' rules, which could allow remote attackers to execute arbitrary code via a specially crafted Web page."
The bug will not be addressed by the forthcoming Patch Tuesday.