Microsoft Security Bulletin (MS00-091) - 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 allows malicious users to pause networking or sometimes crash the entire system by sending a flood of specially malformed TCP packets to port 139. Microsoft FAQ on this issue available here.
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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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