Microsoft's Patch Tuesday Targets Seven VulnerabilitiesMicrosoft's Patch Tuesday Targets Seven Vulnerabilities

Microsoft on Tuesday issued its December security update, addressing seven vulnerabilities.

Three of the vulnerabilities are rated critical. They could allow remote code execution if exploited. Four of the vulnerabilities are rated important.

December's update follows an unusually light November update, which fixed only two flaws. Microsoft's October patch dealt with seven flaws.

The critical vulnerabilities patched this month exist in Microsoft DirectX, Windows Media File Format, and Internet Explorer.

"These are critical because user intervention is required but no credentials are required for the vulnerability to be exploited," said Amol Sarwate, manager of the vulnerability research lab at Qualys, a vulnerability management company.

Sarwate noted that two of the vulnerabilities, MS07-063 and MS07-067, addressed zero-day vulnerabilities.

"Today what's noteworthy is that of the seven bulletins, five of them impact vista," said Eric Schultze, chief technology officer of St. Paul, Minn.-based Shavlik Technologies. "Two of them are specific to Vista and affect only Vista. This month, it looks like Vista is the big loser."

Bulletin MS07-063 addresses a vulnerability in Server Message Block Version 2 (SMBv2), a technology that implements the digital signing of packets so two computers can be sure that they're talking to each other. The flaw could allow an attacker to forge packet signatures.

"This is listed as important and its Vista only, but it's essentially a security feature that Microsoft put into Vista that's allowing this vulnerability to exist," said Schultze. "It's a security feature gone awry."

Bulletin MS07-067 fixes a flaw in the Macrovision secdrv.sys driver in Windows Server 2003 and Windows XP that has been known for three months and, according to Schultze, is being actively exploited. Macrovision offered a driver update to fix the problem last month.

Microsoft also on Tuesday released Microsoft Office 2007 SP1, which improves performance, security and stability for the company's popular productivity suite.