Vulnerability in FFmpeg Matroska Format Decoder Could Allow Remote Code Execution

Executive Summary

Microsoft is providing notification of the discovery and remediation of a vulnerability affecting FFmpeg version 0.8.0 and earlier. Microsoft discovered and disclosed the vulnerability under coordinated vulnerability disclosure to the affected vendor, FFmpeg. FFmpeg has remediated the vulnerability in their software.

A vulnerability exists in the way that the Matroska format decoder included with FFmpeg handles allocation of memory when parsing specially crafted files. An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on user. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

Microsoft Vulnerability Research reported this issue to and coordinated with FFmpeg to ensure remediation of this issue. The vulnerability has been assigned the entry, CVE-2011-3504, in the Common Vulnerabilities and Exposures list. For more information, including information about updates from FFmpeg, see the FFmpeg download page.

Mitigating Factors

• The vulnerability cannot be exploited automatically through e-mail. For an attack to be successful, a user must open an attachment that is sent in an e-mail message.
• In a Web-based attack scenario, an attacker could host a Web site that contains a specially crafted file that is used to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these Web sites. Instead, an attacker would have to convince users to visit the Web site, typically by getting them to click a link in an e-mail message or Instant Messenger message that takes users to the attacker’s Web site, and then convince them to open the specially crafted file.
• An attacker who successfully exploited this vulnerability could gain the same user rights as the logged-on user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.