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Security Bulletin

Microsoft Security Bulletin MS99-057 - Critical

Patch Available for "Malformed Security Identifier Request" Vulnerability

Published: December 16, 1999

Version: 1.0

Originally Posted: December 16, 1999

Summary

Microsoft has released a patch that eliminates a vulnerability in Microsoft® Windows NT® 4.0. The vulnerability could allow a malicious user to cause a Windows NT machine to stop responding to requests for service. The patch for this vulnerability is included in the previously-released patch for the "Syskey Keystream Reuse" vulnerability; customers who have already applied it do not need to take any further action.

Frequently asked questions regarding this vulnerability can be found at https://www.microsoft.com/technet/security/bulletin/fq99-057.mspx.

Issue

The Windows NT Local Security Authority (LSA) provides a number of functions for enumerating and manipulating security information. One of these functions, LsaLookupSids(), is used to determine the Security Identifier (SID) associated with a particular user or group name. A flaw in the implementation of this function causes it to incorrectly handle certain types of invalid arguments. If an affected call were made to this function, it would cause the LSA to crash, thereby preventing the machine from performing useful work.

An affected machine could be put back into service by rebooting, with the loss of any work that was in progress at the time. Remote attacks via this vulnerability would not be possible if NetBios is filtered at the firewall.

Affected Software Versions

  • Microsoft Windows NT Workstation 4.0
  • Microsoft Windows NT Server 4.0
  • Microsoft Windows NT Server 4.0, Enterprise Edition
  • Microsoft Windows NT Server 4.0, Terminal Server Edition

Vulnerability Identifier: CVE-1999-0995

Patch Availability

  • This fix for this vulnerability is included in the patch for the "Syskey Keystream Reuse" vulnerability. Customers who have already applied it do not need to take any additional action.
    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.

Obtaining Support on this Issue

This is a fully supported patch. Information on contacting Microsoft Technical Support is available at </https:>https:.

Acknowledgments

Microsoft acknowledges Anthony Osborne of the Security Labs of McAfee for bringing this issue to our attention.

Revisions

  • December 16, 1999: Bulletin Created.

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