iDefense Security Advisory 04.15.09: IBM AIX muxatmd Buffer Overflow Vulnerability

[iDefense Labs <labs-no-reply@xxxxxxxxxxxx>]

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iDefense Security Advisory 04.15.09
http://labs.idefense.com/intelligence/vulnerabilities/
Apr 15, 2009

I. BACKGROUND

IBM's AIX is a Unix operating system based on System V, which runs on
the PowerPC (PPC) architecture. For more information, visit the product
web site at the following URL.

http://www.ibm.com/systems/power/software/aix/index.html

II. DESCRIPTION

Local exploitation of a buffer overflow vulnerability in IBM Corp.'s
Advanced Interactive eXecutive (AIX) could allow an attacker to gain
root privileges.

The set-uid root binary "muxatmd" concatenates the calling program name
with the static string ".pid". The destination buffer passed to the
function call used for concatenation is a static-sized stack buffer.
Since no bounds checking is performed, a stack-based buffer overflow
can occur when a long program name is given.

III. ANALYSIS

Exploitation of this issue allows an attacker to execute arbitrary code
as root. An attacker would need to construct a malicious application
that runs the "muxatmd" program with a malformed parameter.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in IBM
Corp.'s AIX version 5.3 (5300-09-02-0849). Other versions may also be
affected.

V. WORKAROUND

Removing the set-uid bit from the "/usr/sbin/muxatmd" binary will
provide a workaround for this issue. However, this will make the
program unusable for non-root users.

VI. VENDOR RESPONSE

IBM has released a patch which addresses this issue. For more
information, consult their advisory at the following URL:

http://aix.software.ibm.com/aix/efixes/security/muxatmd_advisory.asc

VII. CVE INFORMATION

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

VIII. DISCLOSURE TIMELINE

12/16/2008  - Initial Vendor Notification
12/16/2008  - Requested PoC
01/06/2009  - PoC Sent
04/15/2009  - Coordinated Public Disclosure

IX. CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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X. LEGAL NOTICES

Copyright © 2009 iDefense, Inc.

Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDefense. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically,
please e-mail customerservice@xxxxxxxxxxxx for permission.

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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