IBM AIX dig dns_name_fromtext Integer Underflow Vulnerability
iDefense Security Advisory 10.30.07
http://labs.idefense.com/intelligence/vulnerabilities/
Oct 30, 2007
I. BACKGROUND
dig is a utility that is commonly used for DNS diagnostics. Under AIX
5.2, the dig program is installed by default and is set-uid root. More
information can be found at the URL shown.
http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.cmds/doc/aixcmds2/dig.htm
II. DESCRIPTION
Local exploitation of an integer underflow vulnerability in the dig
program of IBM Corp.'s AIX operating system allows attackers to execute
arbitrary code with root privileges.
The problem specifically exists within dns_name_fromtext function within
the libdns.a library. This function is called when processing the '-y'
command line parameter to the dig program. By supplying a specially
crafted TSIG key parameter, an attacker is able to cause an integer
underflow, resulting in potentially exploitable heap corruption.
III. ANALYSIS
Exploitation allows an attacker to execute arbitrary code with root
privileges. Local access is required to execute the dig program.
It should be noted that this particular issue is documented within the
bind release notes as bug #1211 and #1350. However, this particular
vulnerability is specific to AIX 5.2 since it installs the dig program
set-uid root.
IV. DETECTION
iDefense has confirmed the existence of this vulnerability within AIX
version 5.2. Previous versions are suspected to be vulnerable. AIX 5.3
is not vulnerable since the dig command is no longer installed set-uid
root.
V. WORKAROUND
Removing the set-uid bit from the dig program will prevent exploitation.
VI. VENDOR RESPONSE
IBM Corp. has addressed this vulnerability by releasing interim fixes.
More information can be found via the Bulletins tab of IBM's
Subscription Service for UNIX and Linux servers. You can reach this
service by clicking the URL shown below.
http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd?mode=1
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-4622 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.
VIII. DISCLOSURE TIMELINE
08/30/2007 Initial vendor notification
09/14/2007 Initial vendor response
10/30/2007 Coordinated public disclosure
IX. CREDIT
The discoverer of this vulnerability wishes to remain anonymous.
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X. LEGAL NOTICES
Copyright © 2007 iDefense, Inc.
Permission is granted for the redistribution of this alert
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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, this information.
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