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iDefense Security Advisory 05.12.09
http://labs.idefense.com/intelligence/vulnerabilities/
May 12, 2009

I. BACKGROUND

Mac OS X is a computer operating systems available from Apple Inc. OS X
is the tenth major version of Apple's operating system for Macintosh
computers and is Unix-based.

For more information, see the vendor's site found at the following link.

http://www.apple.com/support/leopard/internet/

II. DESCRIPTION

Local exploitation of an index validation vulnerability in Apple Inc.'s
Mac OS X xnu kernel could allow an attacker to execute arbitrary code
in the security context of the kernel.

The Mac OS X xnu (Mach) kernel implements workqueues. This allows the
kernel to schedule events to take place in a task. An input validation
error exists within this implementation, which can lead to execution of
arbitrary code in the kernel.

III. ANALYSIS

Exploitation of this issue allows an attacker to execute arbitrary code
in the security context of the kernel. An attacker would need a local
account on a vulnerable system to exploit this issue. Upon successful
exploitation, the attacker could elevate privileges by changing the
effective user id to root of an attacker controlled process.
Alternatively an attacker could also add or alter kernel code in memory
that is commonly referred to as a rootkit.

IV. DETECTION

Apple Inc.'s Mac OS X 10.5.2 and earlier is considered vulnerable to
this issue.

V. WORKAROUND

iDefense is currently unaware of any workaround for this issue.

VI. VENDOR RESPONSE

Apple Inc. has released a patch which addresses this issue. For more
information, consult their advisory at the following URL:

http://support.apple.com/kb/HT3549

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2008-1517 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

03/19/2008  - Initial Contact
03/31/2009  - Attribution Request
04/01/2009  - Attribution Sent
04/01/2009  - CVE Requested
05/12/2009  - Coordinated Public Disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Neil Kettle (mu-b) of
www.digit-labs.org.

Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php

Free tools, research and upcoming events
http://labs.idefense.com/

X. LEGAL NOTICES

Copyright © 2009 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 e-mail 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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