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: http://www.ibm.com/
Author: David Litchfield [ david at ngssoftware.com ]
Relates to: http://www.nextgenss.com/advisories/db2-02.txt
Date of Public Advisory: 5th January 2005
Advisory number: #NISR05012005D
Advisory URL: http://www.ngssoftware.com/advisories/db205012005D.txt

Description
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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.

Details
*******
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 db2java.zip 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
db2java.zip 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 db2java.zip 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.

http://www-306.ibm.com/software/data/db2/udb/support/downloadv8.html - DB2
v8.1
http://www-306.ibm.com/software/data/db2/udb/support/downloadv7.html - DB2
v7.x

NGSSQuirreL for DB2 (http://www.nextgenss.com/db2.htm) can be used to assess
whether your DB2 server is vulnerable to this.


About NGSSoftware
*****************
NGSSoftware design, research and develop intelligent, advanced application
security assessment scanners. Based in the United Kingdom, NGSSoftware have
offices in the South of London and the East Coast of Scotland. NGSSoftware's
sister company NGSConsulting, offers best of breed security consulting
services, specialising in application, host and network security
assessments.

http://www.ngssoftware.com/

Telephone +44 208 401 0070
Fax +44 208 401 0076

enquiries@ngssoftware.com