IBM DB2 JDBC Applet Server buffer overflow (#NISR05012005D)

Type securityvulns
Reporter Securityvulns
Modified 2005-01-06T00:00:00


NGSSoftware Insight Security Research Advisory

Name: IBM DB2 JDBC Applet Server buffer overflow Systems Affected: DB2 8.1 Severity: High risk from remote Vendor URL: Author: David Litchfield [ david at ] Relates to: Date of Public Advisory: 5th January 2005 Advisory number: #NISR05012005D Advisory URL:


IBM's DB2 JDBC Applet Server suffers from a stack based buffer overflow vulnerability that can be exploited remotely without a user ID or password.


When a client connects to the JDBC applet server on TCP port 6789 it does so using a proprietary protocol. The connection packet starts with ValidDb2jdTokenFromTheClientSide and includes the username, the password, the version and the database to connect to.

The problem arises as follows.

Firstly, an attacker attempts to authenticate to the JDBC applet server on TCP 6789 with an overly long username of c. 2200 bytes then disconnects gracefully.

Secondly, they reconnect, but this time send a short username but set the version to something other than expected by the server. Set the version to c. 544 unicode bytes \x00\x41.

An error is logged and at some stage the null terminator is removed and the original username that was sent is concatentated to the version.

This is then copied to a stack based buffer and it overflows.

Fix Information

IBM has written a patch and can be obtained with the latest fixpak. - DB2 v8.1 - DB2 v7.x

NGSSQuirreL for DB2 ( can be used to assess whether your DB2 server is vulnerable to this.

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