FIX: Handle Leak in Windows Media Server Unicast Service (281256)


The information in this article applies to:

  • Microsoft Windows Media Services 4.0
  • Microsoft Windows Media Services 4.1
This article was previously published under Q281256

SYMPTOMS

If a malicious user repeatedly makes and then severs connections, a handle leak can occur in Windows Media Server that may prevent new connections and significantly slow the server's overall performance.

CAUSE

Some applications, such as load balancing and cluster applications, can check the status of a service that Windows Media Server uses. To do this, the applications initiate a Transmission Control Protocol (TCP) handshake to test if the service is listening to a specific TCP port.

In certain cases, Windows Media Server may open a socket handle during the TCP handshake. When the handshake is abruptly terminated, Windows Media Server does not close the socket, and a handle leak in Windows Media Server Unicast Service occurs.

RESOLUTION

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that you determine are at risk of attack. Evaluate your computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to your computer. See the associated Microsoft Security Bulletin to help determine the degree of risk. This fix may receive additional testing. If your computer is sufficiently at risk, Microsoft recommends that you apply this fix now. Otherwise, wait for the next Windows 2000 service pack that contains this fix.

To resolve this problem immediately, download the fix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The following file is available for download from the Microsoft Download Center:

Download Wmsu35924.exe now

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. The English version of this fix should have the following file attributes or later: 
   Date        Time   Version     Size     File name   OS
   ------------------------------------------------------------------
   12/07/2000  11:36  4.1.0.3921  441,840  Nsum.exe    Windows 2000  
   12/07/2000  11:38  4.1.0.3858  440,816  Nsum.exe    Windows NT 4.0

STATUS

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Windows Media Services 4.1.
Modification Type:MinorLast Reviewed:9/23/2005
Keywords:kbHotfixServer kbQFE kbdownload kbbug kbfile kbfix kbgraphxlinkcritical kbQFE kbWin2000PreSP3Fix KB281256
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