Public Vulnerability Reports

SCO Openserver backupsh 'Home' Buffer Overflow Vulnerability

10.24.05

BACKGROUND

SCO OpenServer is a UNIX-like operating system for x86 platforms.

DESCRIPTION

Local exploitation of a buffer overflow vulnerability in The SCO Group
Inc.'s Openserver operating system could allow an attacker to gain
access to the backup group.

The backupsh utility is a standard binary distributed with the Openserver
platform. The vulnerability specifically exists because of a lack of
bounds checking on the value given to the "HOME" environment variable.
Local attackers can supply a specially crafted string to overflow a
stack buffer and execute arbitrary code with group backup privileges.

ANALYSIS

Successful exploitation of this vulnerability will result in execution
of arbitrary code with permissions of the running process. The binary is
setgid backup by default and can be used by attackers with a local
account to gain backup privileges.

DETECTION

iDEFENSE has confirmed the existence of this vulnerability in SCO
Openserver 5.0.7. It is suspected that earlier versions are also
vulnerable.

WORKAROUND

As a workaround solution, remove the setgid bit from the backupsh binary
until a vendor patch can be applied.

# chmod g-s /opt/K/SCO/Unix/5.0.7Hw/usr/lib/sysadm/backupsh

VENDOR RESPONSE

The vendor has released the following advisory for this issue:

ftp://ftp.sco.com/pub/updates/OpenServer/SCOSA-2005.40/SCOSA-2005.40.txt

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2005-2926 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

09/08/2005   Initial vendor notification
09/09/2005   Initial vendor response
10/24/2005   Public disclosure

CREDIT

iDEFENSE Labs is credited with the discovery of this vulnerability.

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LEGAL NOTICES

Copyright © 2005 Verisign, Inc.

Permission is granted for the redistribution of this alert
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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.