Microsoft SQL Server 2000 contains a vulnerability that allows remote attackers to create a denial-of-service condition between two Microsoft SQL servers.
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 address and port number of the SQL server instance that provides access to the requested database.
In addition to providing referrals, the SSRS is capable of replying to "ping" messages from other SQL servers to confirm its presence on a network. When the service receives such a message, it replies to the transmitting host with an identical reply message. In normal operation, the SSRS service is responsible for replying to ping messages sent by an SQL Server and does not initiate them. However, an attacker can create a forged ping message to one instance of the SSRS (Victim A, port 1434) that appears to originate from another instance (Victim B, port 1434), causing Victim A and Victim B to continuously exchange messages. This cycle will continue to consume server and network resources until one of the servers stops sending packets for one of several reasons, including a restart of the SQL Server, a reboot of the server host, or a network failure.
This vulnerability allows remote attackers to initiate a denial-of-service attack between two Microsoft SQL servers.
Apply a patch
Block port 1434/udp
Cisco Systems Inc.
The CERT/CC thanks Microsoft for the information provided in their advisory and NGSSoftware for their discovery and analysis of this vulnerability.
This document was written by Jeffrey P. Lanza.
|Date First Published:||2002-07-26|
|Date Last Updated:||2003-02-05 16:20 UTC|