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Apple Mac OS X xnu Kernel workqueue_additem/workqueue_removeitem Index Validation Vulnerability

14.05.09

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/

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.

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.

DETECTION

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

WORKAROUND

iDefense is currently unaware of any workaround for this issue.

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

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.

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

CREDIT

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

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LEGAL NOTICES

Copyright © 2009 Verisign, Inc.

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