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Microsoft Security Bulletin (MS00-013)
From: secnotif () MICROSOFT COM (Microsoft Product Security)
Date: Wed, 23 Feb 2000 20:36:42 -0800
The following is a Security Bulletin from the Microsoft Product Security
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Microsoft Security Bulletin (MS00-013)
Patch Available for "Misordered Windows Media Services Handshake"
Originally Posted: February 23, 2000
Microsoft has released a patch that eliminates a security vulnerability in
Microsoft(r) Windows Media Services. The vulnerability could allow denial
of service attacks against a streaming media server.
Frequently asked questions regarding this vulnerability and the patch can be
The handshake sequence between a Windows Media server and a Windows Media
Player is asynchronous, because certain resource requests are dependent on
the successful completion of previous ones. If the client-side handshake
packets are sent in a particular misordered sequence, with certain timing
constraints, the server will attempt to use a resource before it has been
initialized and will fail catastrophically, causing the Windows Media
Unicast Service to crash.
The Windows Media Unicast Service can be put back into normal operating
condition by restarting the service, but any sessions that were in effect
at the time of the crash would need to be restarted.
Affected Software Versions
- Microsoft Windows Media Services 4.0 and 4.1
NOTE: Windows NT Server 4.0 customers should upgrade their Windows Media
Services installation to Windows Media Services 4.1 before applying the
patch. Windows Media Services 4.1 can be downloaded for free from
http://www.microsoft.com/windows/windowsmedia/. Windows 2000 Server
includes Windows Media Services 4.1, so the patch can be applied directly
to this configuration.
- Windows NT Server 4.0:
- Windows 2000 Server:
NOTE: Line breaks have been inserted into the above URLs for readability
NOTE: Additional security patches are available at the Microsoft Download
Please see the following references for more information related to this
- Frequently Asked Questions: Microsoft Security Bulletin MS00-013,
- Microsoft Knowledge Base (KB) article Q253943,
Misordered Windows Media Services Handshake Vulnerability,
- Microsoft TechNet Security Web site,
Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft
Technical Support is available at
Microsoft thanks Kit Knox for reporting this issue to us and working with us
to protect customers.
- February 23, 2000: Bulletin Created.
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- Microsoft Security Bulletin (MS00-013) Microsoft Product Security (Feb 24)