Security Identifier Enumeration Function in LSA May Not Handle Argument Properly (248185)

SYMPTOMS

When the LsaLookupSids() function in Windows NT Local Security Authority (LSA) is used to determine the Security Identifier (SID) associated with a particular user or group name, invalid or contradictory arguments passed to the function may not be handled correctly. The result may cause LSA to cease functioning properly and prevent the computer from working. You can restart an affected computer to put it back into service, but any work that was in progress at the time is lost.

NOTE: This vulnerability does not affect computers running Microsoft Windows 2000.

RESOLUTION

Windows NT Server or Workstation 4.0

To resolve this problem, obtain the individual package referenced below or obtain the Windows NT 4.0 Security Rollup Package. For additional information on the SRP, click the article number below to view the article in the Microsoft Knowledge Base:

299444 Post-Windows NT 4.0 Service Pack 6a Security Rollup Package (SRP)

The following files are available for download from the Microsoft Download Center:

Download Q248183.exe for x86-based computers now

Download Q248183.exe for Alpha-based computers now

The English version of this fix should have the following file attributes or later:

   Date       Time     Size      File name    Platform
   ---------------------------------------------------
   11/22/99   03:05p   284,808   Lsasrv.dbg   x86
   11/22/99   03:05p   155,408   Lsasrv.dll   x86

   11/22/99   03:05p    82,260   Lsasrv.dbg   Alpha
   11/22/99   03:05p   253,712   Lsasrv.dll   Alpha

Windows NT Server 4.0, Terminal Server Edition

To resolve this problem, obtain the latest service pack for Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

152734 How to Obtain the Latest Windows NT 4.0 Service Pack

STATUS

Windows NT Server or Workstation 4.0

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

Windows NT Server 4.0, Terminal Server Edition

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT Server 4.0, Terminal Server Edition Service Pack 6.

MORE INFORMATION

LSA provides security services for Windows NT. Among other tasks, it authenticates all logon requests, adjudicates users' privileges, determines whether users can gain access to requested resources, and oversees the security auditing functions. The loss of the LSA service through this vulnerability essentially renders the computer unable to perform any useful work because all requests for services are denied by default.

When a user makes a service request that calls LsaLookupSids(), Windows NT performs a security check to verify that the user has sufficient privileges before fulfilling the request. There is no capability through this vulnerability to bypass the security check. However, the computer stops responding before the check is made, so any user, regardless of privilege, could levy the request and cause the LSA to stop responding. Although it is possible to call LSA functions remotely, doing so requires NetBIOS. If you follow standard recommended security practices, NetBIOS should be filtered through a firewall, preventing an external request from reaching your computer.

For related information about this problem, please visit the following Microsoft Web site:

http://www.microsoft.com/security/bulletins/ms99-057faq.asp

For additional security-related information about Microsoft products, please visit the following Microsoft Web site:

http://www.microsoft.com/security/