IBM AIX invscout Local Command Execution Vulnerability
iDEFENSE Security Advisory 12.20.04 www.idefense.com/application/poi/display?id=171&type=vulnerabilities December 20, 2004
The invscout program is a setuid root application, installed by default under newer versions of IBM AIX, that surveys the host system for currently installed microcode or Vital Product Data (VPD).
Local exploitation of an untrusted path vulnerability in the invscout command included by default in multiple versions of IBM Corp.'s AIX could allow attackers to execute arbitrary code as the root user.
During execution, invscout invokes an external application ("lsvpd") without dropping privileges. This application in turn invokes another external application ("uname"), while trusting the user-specified PATH environment variable. As root privileges are not dropped before this sequence of execution occurs, it is possible for an attacker to gain root access by specifying a controlled path and creating a malicious binary within that path. To exploit the vulnerability, an attacker needs
only to create an executable file called "uname" that contains malicious
code, set the PATH variable to the current directory and execute /usr/sbin/invscout.
Exploitation of this vulnerability allows local attackers to gain increased privileges. Successful explication requires a local account and a writable directory. This directory can be the user's home directory, or even the /tmp directory. Exploitation does not require any knowledge of application internals, making privilege escalation trivial, even for unskilled attackers.
iDEFENSE has confirmed the existence of this vulnerability in IBM AIX version 5.2.0.
Only allow trusted users local access to security critical systems. Alternately, remove the setuid bit from invscout using chmod u-s /usr/sbin/invscout.
VI. VENDOR RESPONSE
"IBM provides the following fixes:
APAR number for AIX 5.1.0: IY64852 (available) APAR number for AIX 5.2.0: IY64976 (available) APAR number for AIX 5.3.0: IY64820 (available)
NOTE: Affected customers are urged to upgrade to 5.1.0, 5.2.0 or 5.3.0 at the latest maintenance level."
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2004-1054 to this issues. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems.
VIII. DISCLOSURE TIMELINE
11/12/2004 Initial vendor notification 11/18/2004 Initial vendor response 12/20/2004 Coordinated public disclosure
iDEFENSE Labs is credited with this discovery.
Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp
X. LEGAL NOTICES
Copyright (c) 2004 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 email firstname.lastname@example.org 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.
Full-Disclosure - We believe in it. Charter: http://lists.netsys.com/full-disclosure-charter.html