__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft Windows Media Player [Vulnerability Note VU#208769] December 8, 2006 21:00 GMT Number R-068 ______________________________________________________________________________ PROBLEM: Windows Media Player does not properly handle malformed Windows Media Metafiles. This vulnerability may allow a remote attacker execute arbitrary code or crash Windows Media Player. PLATFORM: Windows Media Player 7 Windows Media Player for Windows XP Windows Media Player 9 Series Windows Media Player 10 Windows Media Player 11 DAMAGE: May allow a remote attacker execute arbitrary code. SOLUTION: Apply current patches. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. May allow a remote attacker execute ASSESSMENT: arbitrary code. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/r-068.shtml ORIGINAL BULLETIN: http://www.kb.cert.org/vuls/id/208769 ______________________________________________________________________________ [***** Start Vulnerability Note VU#208769 *****] Vulnerability Note VU#208769 Microsoft Windows Media Player fails to properly handle malformed Windows Media Metafiles Overview Windows Media Player does not properly handle malformed Windows Media Metafiles. This vulnerability may allow a remote attacker execute arbitrary code or crash Windows Media Player. I. Description Windows Media Player (WMP) is a multimedia application that comes with Microsoft Windows. According to Microsoft: Advanced Stream Redirector (.asx) files, also known as Windows Media Metafiles, are text files that provide information about a file stream and its presentation. ASX files go beyond the simple task of defining playlists to provide Windows Media Player with information about how to present particular media items of the playlist. Windows Media Metafiles are based on XML syntax and can be encoded in either ANSI or UNICODE (UTF-8) format. They are made up of various elements with their associated tags and attributes. Each element in a Windows Media metafile defines a particular setting or action in Windows Media Player. WMP fails to properly handle Windows Media Metafiles. Specifically, if a URL with an unsupported protocol is embdedded in a Windows Media Metafile and accessed with WMP, a limited heap-based buffer overflow may occur. Note that file extensions for Windows Media Metafiles include .wax, .wvx, .wmx, and .asx. More information concerning Windows Media Player files is available in the Windows Media Player File Name Extensions web page. Exploit code for this vulnerability is publicly available. II. Impact Although the buffer overflow is limited, it may still be possible to corrupt memory in a way that can allow an attacker to execute code or crash WMP. III. Solution We are unaware of a practical solution to this problem. Until a solution is available, the following workaround is strongly encouraged: Do not access Windows Media Metafiles from untrusted sources Attackers may host malicious Windows Media Metafiles on web sites. In order to convince users to visit their sites, those attackers often use a variety of techniques to create misleading links including URL encoding, IP address variations, long URLs, and intentional misspellings. Do not click on unsolicited links received in email, instant messages, web forums, or internet relay chat (IRC) channels. Type URLs directly into the browser to avoid these misleading links. While these are generally good security practices, following these behaviors will not prevent exploitation of this vulnerability in all cases, particularly if a trusted site has been compromised or allows cross-site scripting. Configure Your Web Browser securely handle Windows Media Metafiles Web browsers can be configured to take specific actions for certain types of content, such as Windows Media Metafiles. Configuring your web browser to securely handle Windows Media Metafiles will not correct this vulnerability, but will reduce the chances of exploitation. Mozilla Firefox Configure Mozilla Firefox's Download Actions not to automatically open Windows Media Metafiles. Instructions on how to do this can be found in the Firefox section of Securing Your Web Browser. Microsoft Internet Explorer Setting the Internet Zone security setting to High will prevent Windows Media Metafiles from automatically being opened by Internet Explorer. Instructions on how to do this can be found in the Internet Explorer section of Securing Your Web Browser. Systems Affected Vendor Status Date Updated Microsoft Corporation Vulnerable 8-Dec-2006 References http://blogs.technet.com/msrc/archive/2006/12/07/public-proof-of-concept-code-for-asx-file-format-isssue.aspx http://support.microsoft.com/default.aspx?scid=kb;en-us;Q316992 http://research.eeye.com/html/alerts/zeroday/20061122.html http://www.microsoft.com/windows/windowsmedia/default.mspx http://windowssdk.msdn.microsoft.com/en-us/library/aa385262.aspx Credit This vulnerability was publicly disclosed by sehato. This document was written by Jeff Gennari. Other Information Date Public 11/22/2006 Date First Published 12/08/2006 11:12:57 AM Date Last Updated 12/08/2006 CERT Advisory CVE Name Metric 20.25 Document Revision 27 [***** End Vulnerability Note VU#208769 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of US-Cert for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. 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