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IBM AIX chdev Local Format String Vulnerability
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SUMMARY
The chdev program is "a setuid root application, installed by default
under multiple versions of IBM AIX, that facilitates the changing of
device characteristics". Local exploitation of a format string
vulnerability in the chdev command included by default in multiple
versions of IBM Corp.'s AIX operating system could allow for arbitrary
code execution as the root user.
DETAILS
Vulnerable Systems:
* IBM AIX version 5.2
The vulnerability specifically exists due to an improperly used formatted
printing function. When provided with an incorrect argument (argv[1]) that
contains a format string, the format string will be fed into a formatted
printing function, and the user supplied format string will be evaluated,
allowing for a malicious user to examine stack memory and write to
arbitrary memory locations. With a properly crafted string, this can lead
to the execution of arbitrary code.
Analysis:
This vulnerability can only be exploited by a local user who has been
granted access to the "system" group. Successful exploitation leads to
root-level access.
Due to the nature of the vulnerability, information leakage is trivial and
aids the attacker in exploitation.
Workaround:
Only allow trusted users local access to security critical systems. Only
allow trusted system administrators access to the "system" group.
Alternately, remove the setuid bit from chdev using chmod u-s
/usr/sbin/chdev.
Vendor response:
The vendor has not released a patch for this issue, however, the following
details have been published:
<http://www-1.ibm.com/support/docview.wss?uid=isg1IY67455>
http://www-1.ibm.com/support/docview.wss?uid=isg1IY67455
In addition, a security advisory will be posted at the following site:
<https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mode=1>
https://techsupport.services.ibm.com/server/pseries.subscriptionSvcs?mode=1
Please note that a free signup is required to access the security
advisory.
Disclosure Timeline:
12/21/2004 - Initial vendor notification
01/07/2005 - Initial vendor response
02/07/2005 - Coordinated public disclosure
ADDITIONAL INFORMATION
The information has been provided by
<mailto:customerservice@idefense.com> iDEFENSE.
The original article can be found at:
<http://www.idefense.com/application/poi/display?type=vulnerabilities>
http://www.idefense.com/application/poi/display?type=vulnerabilities
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