SCO Unixware Setuid ptrace Local Privilege Escalation Vulnerability
iDefense Security Advisory 02.24.06
http://www.idefense.com/intelligence/vulnerabilities/display.php?id=395
February 24, 2006
I. BACKGROUND
SCO Unixware is a Unix operating system that runs on many OEM platforms.
More information about the product is available from:
http://www.caldera.com/products/unixware714/
II. DESCRIPTION
Local exploitation of an access validation error in SCO Unixware allows
attackers to gain root privileges.
The vulnerability specifically exists due to a failure to check
permissions on traced executables. The ptrace() system call provides an
interface for debugging other processes on the system. SCO Unixware's
implementation of the ptrace system call fails to check for setuid
permissions on binaries before attaching to the process. This results
in the complete control of memory and execution for the traced process
with root privileges. Attackers can inject data into the running setuid
process and execute arbitrary code with root permissions.
III. ANALYSIS
Exploitation of this vulnerability is trivial. Simply placing shellcode
in the environment and changing the instruction pointer via ptrace() is
enough to elevate privileges.
IV. DETECTION
iDefense has confirmed the existence of this vulnerability in SCO
Unixware versions 7.1.3 and 7.1.4. All previous versions of SCO Unixware
are suspected to be vulnerable.
V. WORKAROUND
It is not possible to reduce the impact of this vulnerability other
than to restrict access to the affected systems.
VI. VENDOR RESPONSE
The vendor has released the following advisory to address this issue:
ftp://ftp.sco.com/pub/updates/UnixWare/SCOSA-2006.9/SCOSA-2006.9.txt
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-2934 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.
VIII. DISCLOSURE TIMELINE
09/15/2005 Initial vendor notification
10/13/2005 Initial vendor response
02/24/2006 Public disclosure
IX. CREDIT
The discoverer of this vulnerability wishes to remain anonymous.
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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
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.
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