Microsoft has released its November security updates, fixing a critical Windows bug that has been exploited by online criminals. Microsoft released just two security updates this month, but security experts say that IT staff will want to install both of them as quickly as possible. The MS07-061 update is particularly critical because the flaw it repairs has been seen in Web-based attack code, said Amol Sarwate, manager of Qualys’s vulnerability research lab. “This was a zero day [flaw] that was being used in the wild by hackers,” he said.

The flaw has to do with the way Windows passes data between applications, using a technology called the URI (Uniform Resource Identifier) protocol handler. This is the part of Windows that allows users to launch applications — an e-mail or instant messaging client, for example — by clicking on a Web link. Because Windows does not perform all of the security checks necessary, hackers found ways to sneak unauthorized commands into these Web links and the flaw could be exploited to install unauthorized software on a victim’s PC. Microsoft’s patch for this problem is rated critical for Windows XP and Windows Server 2003 users, but the bug does not affect Windows 2000 or Vista, Microsoft said. Better update than be angry when someone hacks your computer…