iDefense Security Advisory 11.09.07: IBM Informix Dynamic Server DBLANG Directory Traversal Vulnerability



iDefense Security Advisory 11.09.07
http://labs.idefense.com/intelligence/vulnerabilities/
Nov 09, 2007

I. BACKGROUND

IBM Corp.'s Informix Dynamic Server is an online transaction processing
data server. It contains several set-uid root binaries. For more
information, visit the product homepage at the following URL.

http://www-306.ibm.com/software/data/informix/ids/

II. DESCRIPTION

Local exploitation of a directory traversal vulnerability in IBM Corp.'s
Informix Dynamic Server allows attackers to elevate privileges to root.

This vulnerability exists due to insufficient checking for directory
traversal sequences when processing the DBLANG environment variable. By
using values containing directory traversal specifiers, such as "../",
an attacker can cause set-uid binaries to use Native Language Support
(NLS) message files under their control.

III. ANALYSIS

Exploitation allows local attackers to gain root privileges. In order to
exploit this vulnerability, an attacker would need access to execute one
of the set-uid root binaries that utilizes the DBLANG environment
variable.

Since an attacker can control NLS message file data, they are able to
pass arbitrary format string arguments to the variable argument
function printf(3). Consequently, this vulnerability can be exploited
using publicly known format string exploitation techniques.

When attempting to exploit this vulnerability, it is likely that an
attacker would try to execute code within area of memory that are
considered data. As such, NX, XD, exec-shield, PAX and other data
execution prevention technologies can decrease the likelihood of
success.

IV. DETECTION

iDefense confirmed the existence of this vulnerability in IBM Corp.'s
Informix Dynamic Server version 10.00 UC6TL installed on a Linux
system. Other versions are also suspected as vulnerable. Versions for
other supported Unix systems should also be considered vulnerable.

V. WORKAROUND

Removing the set-uid bit from all programs included with Informix will
prevent exploitation. However, doing so may also disable functionality.

VI. VENDOR RESPONSE

IBM Corp. has addressed this vulnerability within version 10.00.xC7W1 of
Informix Dynamic Server. For more information, visit the following URL.

http://www-1.ibm.com/support/docview.wss?uid=swg27011082

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-5670 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

09/01/2007 Initial vendor notification
09/13/2007 Initial vendor response
11/06/2007 IBM Released 10.00.xC7W1
11/09/2007 Public disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2007 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.



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