Bernhard Mueller has discovered a vulnerability in Microsoft SQL Server, which can be exploited by malicious users to gain escalated privileges.

The vulnerability is caused due to a boundary error in the implementation of the "sp_replwritetovarbin()" SQL procedure. This can be exploited to cause a heap-based buffer overflow via specially crafted arguments passed to the affected procedure.

Successful exploitation may allow execution of arbitrary code with escalated privileges.

The vulnerability is confirmed in Microsoft SQL Server 2000 version 8.00.2050 and Microsoft SQL Server 2005 Express Edition version 9.2.3042.00. Please see vendor advisory for a list of additionally affected products.

Solution
Apply patches.
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Provided and/or discovered by
Bernhard Mueller, SEC Consult.

Changelog
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Original Advisory
MS09-004 (KB959420, KB960082, KB960083, KB960089, KB960090):
http://www.microsoft.com/technet/security/Bulletin/MS09-004.mspx

Microsoft (KB961040):
http://www.microsoft.com/technet/security/advisory/961040.mspx

SEC Consult:
http://www.sec-consult.com/files/20081209_mssql-2000-sp_replwritetovarbin_memwrite.txt

Other references
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Alternate/detailed remediation
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Deep Links
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