Microsoft hands out more Duqu fixes despite prior patch

Microsoft on Tuesday shipped seven patches to address 23 vulnerabilities, including fresh fixes for flaws that could enable the espionage trojan Duqu trojan to spread.

Three of the seven bulletins were rated "critical" by Microsoft, but all of the attention seems squarely focused on one: MS12-034, a rather convoluted fix that remedies 10 issues in Windows, Office, Silverlight and the .NET Framework. 

Three of the 10 vulnerabilities are publicly known, and the most severe of the holes involve the improper handling of TrueType font files, which was the vector by which Duqu is believed to have spread. Duqu was created to conduct reconnaissance of target industrial control systems, and may have been designed to serve as a precursor to another Stuxnet-like attack.

In December, Microsoft patched the Duqu vulnerability, but apparently the code had been replicated in other company products, said Andrew Storms, director of security operations at nCircle, which provides security and compliance auditing solutions.

"This is going to give the patch management folks some serious heartburn," he said in an email of the new patch. "Evidently, Microsoft discovered that the same bits of bad code that were fixed in MS11-087 last year were copied and pasted into other applications, so they needed to fix those, too. Since other changes were pending for those applications, all kinds of other bug fixes not related to Duqu [also] are bundled into this bulletin."

Tuesday's update contains two other high-priority fixes.

MS12-029 corrects a single "critical" weakness in Word that could result in remote code execution by attackers.

Also, MS12-032 remedies one publicly known and one privately disclosed flaw in the TCP/IP stack, a core operating system component. While the bug can at worst result in privilege escalation, but not code execution, a public exploit has been published.

[An earlier version of this story incorrectly stated that the vulnerabilities fixed on Tuesday were helping to spread the Duqu trojan].