Microsoft Security Bulletin (MS00-064)

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Patch Available for "Unicast Service Race Condition" Vulnerability
Originally posted: September 06, 2000

Summary

Microsoft has released a patch that eliminates a security
vulnerability in Microsoft(r) Windows Media(tm) Services. The
vulnerability could allow a malicious user to prevent an affected
server from providing useful service.

Frequently asked questions regarding this vulnerability and the patch
can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-064.asp

Issue

If a client sends a particular type of malformed request to a Windows
Media server, it could induce a race condition. Once the server has
been put into such a state, subsequent requests - even ones that
would normally be legitimate - could cause the Windows Media Unicast
Service to fail. If this happened, any ongoing sessions would be
lost, and the server would stop providing unicast streaming media
services.

An affected server could be put back into service by restarting the
Unicast Service. The vulnerability would not cause any data loss, nor
would it enable the malicious user to usurp any administrative
privileges on the machine.

Affected Software Versions

• Microsoft Windows Media Services 4.0
• Microsoft Windows Media Services 4.1

Patch Availability

• Microsoft Windows Media Services 4.1:
  http://www.microsoft.com/Downloads/Release.asp?ReleaseID=24167

Note: Customers using Windows Media Services 4.0 should upgrade to
Windows Media Services 4.1 and then apply the above patch.

Note: Additional security patches are available at the Microsoft
Download Center

More Information

Please see the following references for more information related to
this issue.

• Frequently Asked Questions: Microsoft Security Bulletin MS00-064,
  http://www.microsoft.com/technet/security/bulletin/fq00-064.asp
• Microsoft Knowledge Base article Q273014 discusses this issue
  and will be available soon.
• Microsoft TechNet Security web site,
  http://www.microsoft.com/technet/security/default.asp

Obtaining Support on this Issue

This is a fully supported patch. Information on contacting Microsoft
Product Support Services is available at
http://support.microsoft.com/support/contact/default.asp.

Acknowledgments

Microsoft thanks Kit Knox of NaviSite (www.navisite.com) for
reporting this issue to us and working with us to protect customers.

Revisions

September 06, 2000: Bulletin Created.