Microsoft Security Bulletin (MS00-091)
   
   Patch Available for "Incomplete TCP/IP Packet" Vulnerability
   
   Originally posted: November 30, 2000
   
Summary

   Microsoft has released a patch that eliminates a security
   vulnerability in Microsoft® Windows NT 4.0 and a recommended
   workaround for Windows 95, 98, 98 Second Edition, and Windows Me. The
   vulnerability could allow a malicious user to temporarily prevent an
   affected machine from providing any networking services or cause it to
   stop responding entirely.
   
   Frequently asked questions regarding this vulnerability and the patch
   can be found at
   http://www.microsoft.com/technet/security/bulletin/fq00-091.asp
   
Issue

   There is a denial of service vulnerability that affects Windows NT 4.0
   Windows 95, 98, 98 Second Edition and Windows Me. By sending a flood
   of specially malformed TCP/IP packets to a victims machine a malicious
   user could cause either of two effects. In the most likely case, the
   flood would temporarily prevent any networking resources on an
   affected computer from responding to client requests; as soon as the
   packets stopped arriving, the machine would resume normal operation.
   In a less likely case, the system could hang, and remain unresponsive
   until it was rebooted.
   
   This vulnerability could only be exploited if TCP port 139 was open on
   the target machine. If the server service or File/Print sharing were
   disabled on a computer it would not be susceptible to this
   vulnerability.
   
Affected Software Versions

     * Windows NT 4.0
     * Windows 95, 98, 98 Second Edition, and Windows Me
       
   Note: Windows 2000 is not affected by this vulnerability.
   
Patch Availability

     * Microsoft Windows NT 4.0 (Intel):
       http://www.microsoft.com/Downloads/Release.asp?ReleaseID=25114
       Note: The patch has been tested on a Windows NT 4.0 computer with
       Service Pack 6a. Customers needing the Alpha version should
       contact PSS under the "Obtaining Support on this Issue" section
       below.
     * Windows 95, 98, 98 Second Edition, and Windows Me:
       As discussed in the FAQ, Microsoft recommends a workaround for
       computers running Windows 95, 98 and 98 Second Edition. Please see
       KB article, Q199346 for more details.
       
   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 MS00-091,
       http://www.microsoft.com/technet/security/bulletin/fq00-091.asp
     * Microsoft Knowledge Base article Q275567,
       http://www.microsoft.com/technet/support/kb.asp?ID=275567
     * 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  BindView's Razor Team (http://razor.bindview.com)
   for reporting these issues to us and helping us protect our customers.
   
Revisions

     * November 30, 2000: Bulletin Created.
       
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     Last updated November 30, 2000
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