iDefense Security Advisory 02.07.08
http://labs.idefense.com/intelligence/vulnerabilities/
Feb 07, 2008

I. BACKGROUND

IBM Corp.'s DB2 Universal Database product is a large database server
product commonly used for high end databases. For more information,
visit the following URL.

http://ibm.com/db2/

II. DESCRIPTION

Local exploitation of a library loading vulnerability in IBM Corp.'s DB2
Universal Database could allow attackers to gain root privileges.

When the DB2INSTANCE environment variable is set, the libdb2 library
will use the corresponding user's directory in place of the DB2
instance directory. This allows an unprivileged local user to control
the directory structure on which several set-uid root binaries operate.

This vulnerability exists due to the way the db2pd binary loads a
library. The program will construct the path to a library to be loaded
by concatenating the path to the instance directory with the static
string "/sqllib/lib/libdb2fmtdmp.so". When an attacker sets the
DB2INSTANCE environment variable to their user name, the binary will
load the library from their directory.

III. ANALYSIS

Exploitation allows local attackers to gain root privileges. In order to
exploit this vulnerability, an attacker must be able to execute the
set-uid root db2pd binary.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in IBM
Corp.'s DB2 Universal Database 9.1 with FixPack 2 installed on a Linux
system. Other versions, including those for other UNIX systems, are
also suspected to be vulnerable.

V. WORKAROUND

In order to mitigate exposure to this vulnerability, implement one of
the following workarounds.

  Using strict permissions for the DB2 instance directory will prevent 
non-instance users from accessing the set-uid root binaries.
  Remove the set-uid bit from the db2pd binary.

VI. VENDOR RESPONSE

IBM Corp. has addressed these vulnerabilities by releasing V9 Fix Pack 4
and version V8 FixPak 16 of its Universal Database product. More
information can be found at the following URLs.

V8: http://www-1.ibm.com/support/docview.wss?uid=swg21256235
V9: http://www-1.ibm.com/support/docview.wss?uid=swg21255572

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-5757 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

03/22/2007  Initial vendor notification
03/23/2007  Initial vendor response
11/13/2007  V9 Fix Pack 4 made available
01/28/2008  V8 Fix Pack 16 made available
02/05/2008  V8 Fix list made available
02/07/2008  Public disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2008 iDefense, 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.