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IBM DB2 Universal Database DB2INSTANCE File Creation Vulnerability

02.22.07

BACKGROUND

IBM Corp.'s DB2 Universal Database product is a large database server product commonly used for higher end databases. For more information, visit http://ibm.com/db2/

DESCRIPTION

Local exploitation of a file creation vulnerability in IBM Corp.'s DB2 Universal Database could allow attackers to elevate privileges to the superuser.

This vulnerability exists due to unsafe file access from within several setuid-root binaries. Specifically, when supplying the DB2INSTANCE environment variable, the setuid-root DB2 administration binaries will use the home directory of the specified user for loading configuration data. This allows attackers create or append to arbitrary files by creating a specific executing environment. Additionally, the user's umask settings will be honored allowing the creation of root-owned world-writable files.

ANALYSIS

Successful exploitation allows a local attacker to gain root privileges.

It should be noted that the attacker does not appear to have a great deal of control over the contents of the data written. However, this does not significantly impact exploitation.

DETECTION

iDefense has confirmed the existence of this vulnerability within IBM Corp.'s DB2 Universal Database 9.1 release installed on Linux. Other versions are suspected to be vulnerable as well.

This vulnerability does not affect DB2 Universal Database running on the windows platform.

WORKAROUND

The best defense against this type of vulnerability is to prevent untrusted users from having code execution abilities on the respective database server. The following workarounds also have value.

Use a more strict permissions setting for the DB2 instance directory would prevent non-instance users from accessing the setuid-root binaries.

Remove the setuid bit from all programs included with DB2.

These configuration changes have not been tested and may cause adverse behavior.

VENDOR RESPONSE

IBM Corp. has addressed this vulnerability within IBM Universal Database DB2 9 Fixpack 2. For more information, consult the corresponding IBM APAR #IY94817 by visiting the following URL.

http://www-1.ibm.com/support/docview.wss?uid=swg21255745

CVE INFORMATION

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not been assigned yet.

DISCLOSURE TIMELINE

11/15/2006 Initial vendor notification
01/29/2007 Initial vendor response
02/22/2007 Coordinated public disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2007 Verisign, Inc.

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Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.