Microsoft has released a patch that addresses a range of vulnerabilities in local procedure call (LPC) functionality and LPC ports. These vulnerabilities include:

•	Invalid LPC request - This vulnerability affects only Windows NT 4.0-based computers. By levying an invalid LPC request, the affected computer may not work.
•	LPC memory exhaustion - This vulnerability affects both Windows NT 4.0-based computers and Windows 2000-based computers. When malicious LPC requests are sent, the number of queued LPC messages may increase and kernel memory may be depleted.
•	Predictable LPC message identifier - This vulnerability affects both Windows NT 4.0-based computers and Windows 2000-based computers. Any process that is aware of the identifier of an LPC message can access it, however, the identifiers can be predicted. In the simplest case, a malicious user can access other processed LPC ports and send them random data as a denial of service attack. In the worst case, the malicious user may be able to send spurious requests to a privileged process to receive additional local privileges.
•	Spoofed LPC port request - This is a new variant of the previously reported "spoofed LPC port request" vulnerability. This vulnerability affects both Windows NT 4.0-based computers and Windows 2000-based computers, and can, under very restricted conditions, allow a malicious user to create a process that runs under the security context of an already-running process, which may include system processes.

NOTE: Because you can use LPC only on the local computer, none of these vulnerabilities can be exploited remotely. Instead, a malicious user can exploit these vulnerabilities only on a computer that the malicious user can log on to interactively. Typically, workstations and terminal server computers are at risk because, if normal security practices are followed, users are not allowed to log on to critical servers interactively. This also means that, even in the worst case, the malicious user can get only additional local privileges and not domain privileges.

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To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

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Windows 2000

The following files are available for download from the Microsoft Download Center:
For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. After applying the hotfix, the Windows 2000 System properties show the system as "Service Pack 1, RC 1.1." This version stamp does not cause any problems. It is simply the version that was coded into the patch. The English-language version of this fix should have the following file attributes or later:

   Date    Time    Version        Size       File name
   ------------------------------------------------------
   7/6/00  1:46pm  5.0.2195.2099  1,659,328  Ntoskrnl.exe
   7/6/00  1:46pm  5.0.2195.2099  1,681,536  Ntkrnlmp.exe
				

NOTE: The Ntkrnlmp.exe file is used only on computers with multiple processors.

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Windows NT 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: The English-language version of this fix should have the following file attributes or later:

   Date    Time    Version        Size       File name
   ------------------------------------------------------
   7/6/00  5:19pm  4.0.1381.7080  934,720   Ntoskrnl.exe
   7/6/00  5:19pm  4.0.1381.7080  955,200   Ntkrnlmp.exe
				

NOTE: The Ntkrnlmp.exe file is used only on computers with multiple processors.

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Windows NT Server 4.0, Terminal Server Edition

To resolve this problem, either obtain the hotfix referenced in this section or the Windows NT Server 4.0, Terminal Server Edition, Security Rollup Package (SRP). For more information about the SRP, click the following article number to view the article in the Microsoft Knowledge Base: A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that you determine are at risk of attack. Evaluate the computer's physical accessibility, network and Internet connectivity, and other factors to determine the degree of risk to the computer. See the associated Microsoft Security Bulletin (http://www.microsoft.com/technet/security/bulletin/MS00-070.mspx) to help determine the degree of risk. This hotfix may receive additional testing. If the computer is sufficiently at risk, we recommend that you apply this hotfix now.

To resolve this problem immediately, download the hotfix by following the instructions later in this article or contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site: Note In special cases, charges that are ordinarily incurred for support calls may be canceled, if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The following file is available for download from the Microsoft Download Center:
Release Date: October 12, 2001

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. NOTE: After you apply this patch, the operating system version changes from Build 1381: Service Pack 6 to Build 1381: Service Pack 6, RC1.6. This change in the displayed version number does not cause any errors or issues.

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

   Date         Time   Version         Size       File name
   -----------------------------------------------------------
   29-Jan-2001  11:46  4.0.1381.33474  1,003,392  Ntkrnlmp.exe
   29-Jan-2001  11:39                    156,496  Ntldr
   29-Jan-2001  11:46  4.0.1381.33474    982,144  Ntoskrnl.exe
				

NOTE: Due to file dependencies, this update requires Windows NT Server 4.0, Terminal Server Edition Service Pack 6.

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Windows 2000

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Windows 2000. This problem was first corrected in Windows 2000 Service Pack 2.

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Windows NT 4.0

Microsoft has confirmed that this problem may cause a degree of security vulnerability in Windows NT 4.0.

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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.

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For additional information about this issue, view the following Microsoft Web site: Frequently asked questions about this vulnerability are available on the following Microsoft Web site:

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