Microsoft SQL Server User Authentication Remote Buffer Overflow Vulnerability



Date Discovered

August 6, 2002


A vulnerability has been discovered in Microsoft SQL Server that could make it possible for remote attackers to gain access to target hosts. It is possible for an attacker to cause a buffer overflow condition on the vulnerable SQL server with a malformed login request. This may allow a remote attacker to execute arbitrary code as the SQL Server process. This vulnerability reportedly occurs even before authentication can proceed.

Technologies Affected

  • Microsoft Data Engine 2000
  • Microsoft SQL Server 2000
  • Microsoft SQL Server 2000 SP1
  • Microsoft SQL Server 2000 SP2


Block external access at the network boundary, unless external parties require service.
Blocking access to the SQL Server port (1433) at the network boundary may reduce exposure to exploitation.

Microsoft has revised their advisory. Microsoft recommends that users of SQL 2000 and MSDE 2000 apply the patch from MS02-061 which contains additional security fixes:



Reported by Dave Aitel <>.

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