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IBM AIX pioout Arbitrary Library Loading Vulnerability

07.26.07

BACKGROUND

The pioout program is a setuid root application, installed by default under multiple versions of IBM AIX, that is used to interface with the printer driver. More information can be found at the following URL.

http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.cmds/doc/aixcmds4/pioout.htm

DESCRIPTION

Local exploitation of an arbitrary library loading vulnerability in the 'pioout' program, as included with IBM Corp.'s AIX operating system, allows an attacker to execute arbitrary code with root privileges.

The vulnerability exists due to the application loading an arbitrary shared library provided by the attacker, without dropping privileges. Using the -R command line argument, an attacker can specify a shared library used to parse data coming from the printer.

ANALYSIS

Exploitation of this vulnerability results in the execution of arbitrary code with root privileges.

The pioout program is setuid root, and executable by any user with local access. To exploit the vulnerability, all an attacker has to do is create a shared library that executes a shell.

DETECTION

iDefense has confirmed the existence of this vulnerability in AIX version 5.3 with service pack 6. Previous versions may also be affected.

WORKAROUND

Removing the setuid bit from the binary will prevent exploitation, but may make the program unusable by non-root users.

VENDOR RESPONSE

IBM Corp. has addressed this vulnerability by releasing interim fixes. More information can be found via the Bulletins tab of IBM's Subscription Service for UNIX and Linux servers. You can reach this service by clicking the URL shown below.

http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd?mode=1

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-4003 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.

DISCLOSURE TIMELINE

06/05/2007 Initial vendor notification
06/08/2007 Initial vendor response
07/26/2007 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.