Microsoft Corp. today released six security bulletins detailing patches for nine separate flaws across several of its products as part of its monthly updates for November.
Seven of the flaws were rated "critical" by the company, while the other two were rated "important."
The most dangerous of the vulnerabilities in this month's batch is a flaw in Microsoft's Workstation Service memory, according to security vendor Symantec Corp. The flaw is remotely executable and allows attackers to potentially take complete control of compromised systems to create new user accounts, install programs and view, modify or delete data.
"A successful exploitation of this vulnerability could result in a complete system compromise," Symantec said in its advisory. "This issue can be exploited by remote anonymous attackers on Windows 2000, Windows XP and possibly Windows Server 2003 systems." Symantec added that a wide variety of component technologies and services are affected by this issue.
A remotely exploitable flaw in Microsoft XML Core Services poses another critical threat to enterprises because it has already been publicly disclosed, said Michael Sutton, security evangelist at Web application security firm SPI Dynamics Inc.
As with the Workstation Service flaw, attackers who successfully exploit this vulnerability could take complete administrative control of systems, Microsoft said in its advisory. Enterprises need to make patching this flaw a top priority because public exploits have already started becoming available, Sutton said.
Also important from an enterprise standpoint is the cumulative update Microsoft issued today to fix three separate remotely exploitable vulnerabilities in Internet Explorer, Sutton said. Two of the flaws addressed in the bulletin -- both involving DirectAnimation ActiveX controls -- have already been publicly disclosed, and exploit code for them has begun circulating, he said. November's security update is smaller than others this year in terms of the overall number of patches announced, according to Mark Allen, data manager at Shavlik Technologies LLC. "But the percentage that are critical and remotely exploitable is still pretty high," he noted. Patches for those are definitely worth deploying as quickly as possible, he said.
All of the flaws addressed by the current set of fixes -- except for the one in Workstation Service -- can be exploited over the Internet, though they require users to either go to malicious Web sites or click on malicious e-mails, Allen said.
The Workstation Service flaw, on the other hand, only requires an attacker to send a specially crafted packet to the network to be exploited, he said. "The potential for exploiting this one is pretty high," he added.