Syskey Keystream Reuse Vulnerability

A vulnerability exists in Syskey, a utility that provides additional protection for Microsoft® Windows NT® password databases. The vulnerability allows a particular cryptanalytic attack to be effective against Syskey, significantly reducing the strength of the protection it offers.

Issue

Syskey is a utility that strongly encrypts the hashed password information in the SAM database in order to protect it against offline password cracking attacks. However, Syskey reuses the keystream used to perform some of the encryption. This significantly reduces the strength of the protection it provides by enabling a well-known cryptanalytic attack to be used against it.

A patch is available that eliminates the key reuse vulnerability and again makes it computationally infeasible to mount a brute-force attack against the SAM database when Syskey has been applied.

Affected Products

• Windows NT Server, Enterprise, Terminal Server and Workstation 4.0

Download

Patch: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=16798

Further Details

Source: Microsoft Corporation

Reference: Microsoft Corporation

Updated: December 16, 1999

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