QNX Neutrino RTOS su Command Buffer Overflow

iDefense Security Advisory 02.07.06
http://www.idefense.com/intelligence/vulnerabilities/display.php?id=385
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 buffer overflow in QNX Neutrino RTOS's (QNX)
'su' command allows attackers to gain root privileges. The problem
specifically exists in the parsing of a long string passed as the first
argument to the set user id (setuid) binary 'su'. The 'su' command is
intended for running commands under a substitute user or group id. A
string larger then approximately 4000 bytes causes a stack overflow
directly overwriting the stored return address and allowing an attacker
to seize CPU control and eventually execute arbitrary code under root
privileges.

III. ANALYSIS

Any authenticated local attacker can exploit this vulnerability to gain
super-user (root) privileges on the affected system.

IV. DETECTION

iDefense has confirmed the existence of these vulnerabilities in QNX
Neutrino RTOS version 6.2.0. Earlier versions are suspected to be
susceptible to exploitation as well.

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

06/04/2004  Initial vendor notification
02/07/2006  Public disclosure

IX. CREDIT

Texonet (www.texonet.com) is credited with this discovery.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, Inc.

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