Microsoft Security Bulletin MS00-032 - Critical
Patch and Tool Available for "Protected Store Key Length" Vulnerability
Published: June 01, 2000 | Updated: January 08, 2001
Originally Posted: June 01, 2000
Updated: January 8, 2001
On June 01, 2000, Microsoft released the original version of this bulletin. However, an error was subsequently discovered in the patch, and on July 26, 2000, Microsoft released a corrected version.
Microsoft has released a patch and a tool that eliminate a security vulnerability in Microsoft® Windows® 2000. The vulnerability could make it easier for a malicious user who had complete control over a Windows 2000 machine to compromise users' sensitive information.
Frequently asked questions regarding this vulnerability and the patch can be found at http://www.microsoft.com/technet/security/bulletin/fq00-032.mspx
A Protected Store is provided as part of CryptoAPI, in order to provide secure storage for sensitive information such as private keys and certificates. By design, the Protected Store should always encrypt the information using the strongest cryptography available on the machine. However, the Windows 2000 implementation uses 40-bit key to encrypt the Protected Store, even if stronger cryptography is installed on the machine.
This vulnerability weakens the protection on the Protected Store, but does not eliminate it. An attacker would need to gain complete administrative control over the machine that houses the Protected Store in order to gain access to it, and even then would still need to mount a brute-force cryptographic attack against it. However, customers who follow the recommended remediation for this vulnerability can ensure that such an attack would be significantly more difficult, if not impossible.
The patch package to eliminate this vulnerability contains a new version of PSBASE.DLL, the module that provides the Protected Store functionality, and a tool named Keymigrt.exe. Installing PSBASE.DLL will ensure that all future additions to the Protected Store are encrypted using the strongest cryptography available on the machine. However, the Keymigrt tool also needs to be run, in order to re-encrypt all items currently in the Protected Store. We recommend that system administrators place the Keymigrt tool into users' logon scripts to ensure that the tool is run the next time they log on.
Affected Software Versions
- Windows 2000 Professional
- Windows 2000 Server
- Windows 2000 Advanced Server
Vulnerability Identifier: CAN-2000-0487
Note: The patch can be applied atop Windows 2000 Gold, and will be included in Windows 2000 Service Pack 1. However, regardless of how the patch is applied, keymigrt still must be run one time, to re-encrypt all its already in the Protected Store.
Note: To obtain the Keymigrt tool, run the patch using the -x option, to extract the patch contents. Keymigrt.exe will be one of the files extracted.
Note: Additional security patches are available at the Microsoft Download Center
Please see the following references for more information related to this issue.
- Frequently Asked Questions: Microsoft Security Bulletin MS00-032, http://www.microsoft.com/technet/security/bulletin/fq00-032.mspx
- Microsoft Knowledge Base (KB) article 260219, http://support.microsoft.com/default.aspx?scid=kb;en-us;260219
- Microsoft TechNet Security web site, http://www.microsoft.com/technet/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.
- June 01, 2000: Bulletin Created.
- July 26, 2000: Updated to correct a regression and packaging problem with the original patch.
- January 08, 2001: Updated to clarify the method of obtaining the keymigrt tool, and to clarify that the patch functionality, but not the keymigrt functionality, is provided in SP1.
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