Microsoft Security Bulletin MS99-057 - Critical
Patch Available for "Malformed Security Identifier Request" Vulnerability
Published: December 16, 1999
Originally Posted: December 16, 1999
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 http://www.microsoft.com/technet/security/bulletin/fq99-057.mspx.
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
- 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
Please see the following references for more information related to this issue.
- Microsoft Security Bulletin MS99-057: Frequently Asked Questions, http://www.microsoft.com/technet/security/bulletin/fq99-057.mspx.
Microsoft Knowledge Base (KB) article 248185, SID Enumeration Function in LSA may not Handle Argument Properly, http://support.microsoft.com/default.aspx?scid=kb;en-us;248185&sd=tech.
(Note: It may take 24 hours from the original posting of this bulletin for this KB article to be visible.)
Microsoft Security web site, http://www.microsoft.com/security/default.mspx.
Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft Technical Support is available at http://support.microsoft.com/contactussupport/?ws=support.
Microsoft acknowledges Anthony Osborne of the Security Labs of McAfee for bringing this issue to our attention.
- December 16, 1999: Bulletin Created.
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