Public Vulnerability Reports

Apple Computer Mac OS X pppd Plugin Loading Privilege Escalation Vulnerability

05.24.07

BACKGROUND

Apple Mac OS X pppd is a setuid root application that is used to establish and configure connections for point to point links. It is commonly used for configuring traditional dial-up modem and DSL connections. More information can be found at the following URL.

http://developer.apple.com/documentation/Darwin/Reference/Manpages/man8/pppd.8.html

DESCRIPTION

Local exploitation of a privilege escalation vulnerability in Apple Computer Inc.'s Mac OS X pppd could allow an attacker to gain root privileges.

The vulnerability exists due to insufficient access validation when processing the "plugin" command line option. The application does not properly verify that the requesting user has root privileges and allows any user to load plug-ins.

When checking to see if the executing user has root privileges, a check is made to see if the stdin file descriptor is owned by root. Passing this check is trivial and allows the attacker to load arbitrary plug-ins resulting in arbitrary code execution with root privileges.

ANALYSIS

Exploitation is trivial and grants root access.

This vulnerability cannot be triggered remotely; an attacker needs local access to the victim's system in order to exploit this vulnerability. pppd is installed by default.

DETECTION

iDefense has confirmed the existence of this vulnerability in version 10.4.8 of Mac OS X. Other versions may also be affected.

WORKAROUND

Remove the setuid bit from the pppd binary. This will prevent users without root privileges from being able to properly use the program.

VENDOR RESPONSE

Apple Inc has addressed this vulnerability in Apple Security Update 2007-005. More information can be found from Apple's Security Update page or the Security Update 2007-005 advisory page at the respective URLs below.

http://docs.info.apple.com/article.html?artnum=61798

http://docs.info.apple.com/article.html?artnum=305530

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-0752 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

01/08/2007 Initial vendor notification
01/09/2007 Initial vendor response
05/24/2007 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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