The company said that Windows 2000 Service Pack 4, Windows XP, and Windows Server 2003 are vulnerable and that Windows Vista and Windows Server 2008 are not vulnerable.
The flaw could allow a remote attacker to execute malicious code by convincing or duping a user to open a specially crafted QuickTime media file or to visit a Web page that features QuickTime media file of this sort.
The vulnerability is not in Apple's QuickTime media software or in Microsoft Internet Explorer browser; it's in the DirectShow platform (quartz.dll). Nonetheless, Web browsers -- Internet Explorer and others -- represent an avenue of potential infection for users of vulnerable versions of Windows.
"While the vulnerability is NOT in IE or other browsers, a browse-and-get-owned attack vector does exist here via the media playback plug-ins of browsers," Microsoft security software engineer Chengyun Chu explained in a post on the Microsoft Security Research and Defense (MSRC) blog. "The attacker could construct a malicious Web page which uses the media playback plug-ins to play back a malicious QuickTime file to reach the vulnerability in Quartz.dll."
A successfully executed attack would give the attacker the same file access rights as the affected user. For users with administrative rights, the risk is greater than for users with more restricted rights.
Microsoft said it "is aware of limited, active attacks that use this exploit code." Chu has posted several steps that users can take to protect themselves on the MSRC blog.
Earlier this month, Microsoft issued a security advisory about an authentication bypass vulnerability in certain Microsoft Internet Information Services configurations.
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