DigitMemo.com

The November security updates fix the so-called URI problem, a critical Windows bug that has been exploited by online criminals.

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.

The second vulnerability, rated “important” by Microsoft, has to do with Windows DNS (Domain Name System) servers, which are used to exchange information about the location of computers on the Internet. Attackers could exploit this flaw to redirect victims to malicious Web sites without their knowledge, something known as a “man in the middle” attack. “All system administrators should look very closely at this vulnerability,” Sarwate said. “I would have personally rated it as critical,” he said.