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AUSCERT External Security Bulletin Redistribution
ESB-2004.0798 -- iDEFENSE Security Advisory 12.20.04
IBM AIX invscout Local Command Execution Vulnerability
21 December 2004
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AusCERT Security Bulletin Summary
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Product: invscout
Publisher: iDEFENSE
Operating System: AIX
Impact: Execute Arbitrary Code/Commands
Root Compromise
Access: Existing Account
CVE Names: CAN-2004-1054
Original Bulletin: http://www.idefense.com/application/poi/display?id=171
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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
I. BACKGROUND
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).
II. DESCRIPTION
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.
III. ANALYSIS
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.
IV. DETECTION
iDEFENSE has confirmed the existence of this vulnerability in IBM AIX
version 5.2.0.
V. WORKAROUND
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
IX. CREDIT
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 customerservice@idefense.com 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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