Public Vulnerability Reports

IBM AIX muxatmd Buffer Overflow Vulnerability

04.15.09

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

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.

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.

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.

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.

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

CVE INFORMATION

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

DISCLOSURE TIMELINE

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

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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