Software Engineering Institute

The SQL Server Resolution Service (SSRS) was introduced in Microsoft SQL Server 2000 to provide referral services for multiple server instances running on the same machine. The service listens for requests on UDP port 1434 and returns the IP address and port number of the SQL server instance that provides access to the requested database.

The SSRS contains a heap buffer overflow that allows an attacker to execute arbitrary code by sending a crafted request to port 1434/udp. The code within such a request will be executed by the server host with the privileges of the SQL Server service account.

This vulnerability allows unauthenticated remote attackers to execute arbitrary code with the privileges of the SQL service account. If the privileges of the service account are elevated via VU#796313, this vulnerability may result in compromise of the server host.

Apply a patch

This vulnerability was originally addressed by Microsoft in Security Bulletin MS02-039. In January 2003, Microsoft updated MS02-039 to recommend that customers apply the patch from Microsoft Security Bulletin MS02-061, which addresses additional vulnerabilities. For more information, please see

Block port 1434/udp

As a workaround, system administrators can use a firewall to block port 1434/udp at an appropriate network border, thus preventing external attackers from exploiting this vulnerability.