Security Identifier Enumeration Function in LSA May Not Handle Argument Properly

ID: Q248185

The information in this article applies to:

Microsoft Windows NT Server versions 4.0 SP4, 4.0 SP5, 4.0 SP6
Microsoft Windows NT Server, Enterprise Edition version 4.0
Microsoft BackOffice Server version 4.0
Microsoft BackOffice Small Business Server version 4.0
Microsoft Cluster Server, versions 1.0, 1.1

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

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

The following files are available for download from the Microsoft Download Center. Click the file names below to download the files:

Q248183.Exe for x86-based computers

Q248183.Exe for Alpha-based computers

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

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.

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/

Additional query words:

Keywords : kbnetwork ntsecurity ntsp kbbug4.00 kbfix4.00
Version : winnt:1.0,1.1,4.0,4.0 SP4,4.0 SP5,4.0 SP6
Platform : winnt
Issue type : kbbug