IBM AIX ipl_varyon Local Buffer Overflow Vulnerability
iDEFENSE Security Advisory 02.10.05
www.idefense.com/application/poi/display?id=196&type=vulnerabilities
February 10, 2005
I. BACKGROUND
The ipl_varyon program is a setuid root application, installed by
default under multiple versions of IBM AIX, which can be used to set the
default physical boot volume.
II. DESCRIPTION
Local exploitation of a buffer overflow vulnerability in the ipl_varyon
command included by default in multiple versions of IBM Corp.'s AIX
Operating System could allow for arbitrary code execution as the root
user.
The vulnerability specifically exists due to an unbounded
string copy operation. When provided with a long argument to the -d
option, the ipl_varyon process will overwrite stack memory with the user
supplied string. This allows for overwriting of the saved return address
on the stack, which in turn allows for complete control over execution
flow.
III. ANALYSIS
Exploitation of this vulnerability is simple for a skilled attacker,
however gid "system" is required in order to execute the vulnerable
binary. Successful exploitation yields root access on the system.
IV. DETECTION
iDEFENSE has confirmed the existence of this vulnerability in IBM AIX
version 5.2. It is suspected that previous versions are also vulnerable.
V. WORKAROUND
Only allow trusted users local access to security critical systems; only
allow trusted users access to the "system" group. Alternately, remove
the setuid bit from netpmon using chmod u-s /usr/sbin/ipl_varyon
VI. VENDOR RESPONSE
Vendor advisories for this issue are available at:
For AIX 5.1:
https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod
e=1&heading=AIX51&topic=SECURITY&month=ALL
For AIX 5.2:
https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod
e=1&heading=AIX52&topic=SECURITY&month=ALL
For AIX 5.3:
https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mod
e=1&heading=AIX53&topic=SECURITY&month=ALL
VII. CVE INFORMATION
A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.
VIII. DISCLOSURE TIMELINE
12/21/2004 Initial vendor notification
01/07/2004 Initial vendor response
02/10/2004 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) 2005 iDEFENSE, 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,
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