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AA-2006.0098                  AUSCERT Advisory

                                   [Win]
Vulnerability in Windows Media Player may allow execution of arbitrary code
                             11 December 2006
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        AusCERT Advisory Summary
        ------------------------

Product:              Windows Media Player 10.x
Operating System:     Windows
Impact:               Execute Arbitrary Code/Commands
                      Denial of Service
Access:               Remote/Unauthenticated
Member content until: Monday, January 08 2007

OVERVIEW

        A vulnerability in Windows Media Player 10's handling of ASX files
        may allow a remote attacker to execute arbitrary code or commands,
        or cause Windows Media Player to crash. [1]

        Note that the vendor has not confirmed this vulnerability and is
        currently investigating its status.


IMPACT

        Opening an ASX file or viewing a web page with an ASX file embedded
        may allow a remote attacker to execute arbitrary code with the same
        privileges as the user viewing the file. If the user is running as
        an administrator, this could lead to a system compromise.


MITIGATION

        Until a patch is released, users are advised to disable Windows
        Media Player from automatically opening .ASX files.

        This can be achieved via Windows Explorer. Under the Tools menu,
        select Folder Options. Open the File Types tab and change the
        program that handles .ASX files to something other than Windows
        Media Player.

        This change can also be made directly in the Registry, which may
        be useful for automation over a large network.

        Under the registry keys:

        HKEY_USERS\<ALL USER GUIDS>\Software\Microsoft\Windows\
            CurrentVersion\Explorer\FileExts\.asx

        set the Application key to a program other than Windows Media
        Player. [2]


REFERENCES

        [1] http://blogs.technet.com/msrc/archive/2006/12/07/public-proof-of-concept-code-for-asx-file-format-isssue.aspx

        [2] http://research.eeye.com/html/alerts/zeroday/20061122.html

AusCERT has made every effort to ensure that the information contained
in this document is accurate.  However, the decision to use the information
described is the responsibility of each user or organisation. The decision to
follow or act on information or advice contained in this security bulletin is
the responsibility of each user or organisation, and should be considered in
accordance with your organisation's site policies and procedures. AusCERT
takes no responsibility for consequences which may arise from following or
acting on information or advice contained in this security bulletin.

If you believe that your computer system has been compromised or attacked in 
any way, we encourage you to let us know by completing the secure National IT 
Incident Reporting Form at:

        http://www.auscert.org.au/render.html?it=3192

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
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