On a shared computer, it may be possible for a malicious user to interactively log on to the computer and compromise the security of the cryptographic keys of other users who subsequently log on to the same computer.

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This vulnerability involves a registry key that is used to specify the dynamic-link library (DLL) for a hardware accelerator in the default Cryptographic service providers (CSPs) that are included with Cryptography Application Programming Interface (CryptoAPI). By design, such a DLL has access to users' public and private keys. Although only administrators should have permission to add such a DLL, the permissions on the key could allow any user who can interactively log on to the computer to do so. By writing a DLL and installing it, a malicious user could compromise the keys of other users who subsequently use the computer.

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

   Date      Time    Size    File name     Platform
   ------------------------------------------------
   04/11/00  08:19p  41,744  Regacl40.exe  Intel
   04/12/00  03:43p  95,504  Regacl40.exe  Alpha
				

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Microsoft Windows NT Server version 4.0, Terminal Server Edition

To resolve this problem, obtain the Windows NT Server 4.0, Terminal Server Edition, Security Rollup Package (SRP). For additional information about the SRP, click the article number below to view the article in the Microsoft Knowledge Base:

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

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The computers primarily at risk are workstations and servers running Terminal Server Edition. If you follow typical security recommendations, typical users are not allowed to interactively log on to domain controllers, Web servers, database servers, ERP servers, and other security-critical computers. A tool is available that resets the permissions on the key to the correct default values. In addition, it incorporates the functionality of the tool provided in Microsoft Security Bulletin MS00-008 located at the following Microsoft Web site: This issue affects only computers running Windows NT 4.0; it does not affect computers running Microsoft Windows 2000.

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

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