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Apple Mac OS X Mach Port Inheritance Privilege Escalation Vulnerability

11.14.07

BACKGROUND

Mach ports are used to provide inter-process communication (IPC) facilities on Mac OS X. More information can be found on the vendor's site at the following URL.

http://developer.apple.com/documentation/Darwin/Conceptual/KernelProgramming/boundaries/chapter_14_section_4.html

DESCRIPTION

Local exploitation of an access validation vulnerability in Apple Inc.'s Mac OS X could allow an attacker to execute arbitrary code with root privileges.

When executing a setuid-root binary, the Mach kernel does not reset the current thread Mach port, or the current thread Mach Exception Port. By first creating and obtaining write access to a Mach port, and then executing a set-uid root binary, an attacker can write arbitrary data into the address space of the process running as root. This leads to arbitrary code execution in the privileged process.

ANALYSIS

Successful exploitation of this vulnerability results in the execution of arbitrary code with root privileges. All an attacker needs is a setuid-root binary and permission to execute it. In a default install, there are numerous binaries that meet these requirements.

DETECTION

iDefense has confirmed the existence of this vulnerability in Mac OS X version 10.4.10, both Server and Workstation. Previous versions may also be affected.

WORKAROUND

iDefense is currently unaware of any workaround for this issue.

VENDOR RESPONSE

Apple addressed this vulnerability within their Mac OS X 2007-008 security update. More information is available at the following URL.

http://docs.info.apple.com/article.html?artnum=307041

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-3749 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

09/07/2007 Initial vendor notification
09/10/2007 Initial vendor response
11/14/2007 Coordinated public disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2007 Verisign, 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, this information.