QNX Neutrino RTOS phfont Race Condition Vulnerability

iDefense Security Advisory 02.07.06
http://www.idefense.com/intelligence/vulnerabilities/display.php?id=383
February 7, 2006

I. BACKGROUND

QNX Software Systems Ltd.'s Neutrino RTOS (QNX) is a real-time operating
system designed for use in embedded systems. More information is
available at:

  http://www.qnx.com/products/rtos/

II. DESCRIPTION

Local exploitation of a race condition vulnerability in QNX Neutrino
RTOS's (QNX) phfont command allows attackers to gain root privileges.

QNX Neutrino RTOS is a real-time operating system designed for use in
embedded systems. The problem specifically exists because phfont spawns
another command, phfontphf, without proper sanity checking. A local
attacker can create a malicious replacement for this command and cause
it to be executed in place of the original by manipulating the PHFONT
and PHOTON2_PATH environment variables. phfont is installed set user id
root by default.

III. ANALYSIS

Successful exploitation provides local attackers with super user
privileges on the affected system, allowing for complete control.

IV. DETECTION

iDefense has confirmed the existence of these vulnerabilities in QNX
Neutrino RTOS version 6.2.1. Earlier versions are also suspected to be
susceptible to exploitation.

V. WORKAROUND

Clear the set user ID or execute bits from the affected binary or remove
it entirely.

VI. VENDOR RESPONSE

The vendor has not responded to communication regarding this issue.

VII. CVE INFORMATION

A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.

VIII. DISCLOSURE TIMELINE

09/29/2004  Initial vendor notification
02/07/2006  Public disclosure

IX. CREDIT

Knud Hojgaard (http://kokanin.dtors.net) is credited with this discovery.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, 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
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