SCO OpenServer Buffer Overflow in authsh and backupsh Lets Local Users Gain Elevated Privileges
SecurityTracker Alert ID: 1015099|
SecurityTracker URL: http://securitytracker.com/id/1015099
(Links to External Site)
Date: Oct 25 2005
Execution of arbitrary code via local system, Root access via local system, User access via local system|
Fix Available: Yes Vendor Confirmed: Yes |
iDEFENSE reported a vulnerability in SCO OpenServer in authsh and backupsh. A local user can gain root privileges on the target system.|
The authsh and backupsh utilities do not properly validate user-supplied input in the HOME environment variable. A local user can set a specially crafted value to trigger a stack overflow and execute arbitrary code.
With authsh, the code will run with 'auth' group privileges. These privileges allow a local user to obtain root privileges by modifying authentication data.
With backupsh, the code will run with 'backup' group privileges.
The vendor was notified on September 8, 2005.
iDEFENSE Labs discovered this vulnerability.
The original advisories are available at:
A local user can execute arbitrary code to potentially gain root privileges on the target system.|
The vendor has issued the following fixes for OpenServer 5.0.7:|
Location of Fixed Binaries
MD5 (VOL.000.000) = ebcf85edb0e7c8c0a3af4cec65a27ed7
Upgrade the affected binaries with the following sequence:
1) Download the VOL* files to a directory
2) Run the custom command, specify an install from media
images, and specify the directory as the location of the
The vendor's advisory is available at:
Vendor URL: www.sco.com/ (Links to External Site)
|Underlying OS: UNIX (Open UNIX-SCO)|
Source Message Contents
Subject: iDEFENSE Security Advisory 10.24.05: SCO Openserver authsh 'Home'|
SCO Openserver authsh 'Home' Buffer Overflow Vulnerability
iDEFENSE Security Advisory 10.24.05
October 24, 2005
SCO OpenServer is a UNIX-like operating system for x86 platforms.
Local exploitation of a buffer overflow vulnerability in The SCO Group
Inc.'s Openserver operating system could allow an attacker to gain root
The authsh 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 auth privileges.
Successful exploitation of this vulnerability will result in execution
of arbitrary code with permissions of the running process. The binary is
setgid auth by default and can be used by attackers with a local account
to gain root privileges, as the group auth has write access to system
authentication information. An attacker would only need to modify the
system passwd file to grant an account they control superuser
iDEFENSE has confirmed the existence of this vulnerability in SCO
Openserver 5.0.7. It is suspected that earlier versions are also
As a workaround solution, remove the setgid bit from the authsh binary
until a vendor patch can be applied.
# chmod -g /opt/K/SCO/Unix/5.0.7Hw/usr/lib/sysadm/authsh
VI. VENDOR RESPONSE
The vendor has released the following advisory for this issue:
VII. 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
VIII. DISCLOSURE TIMELINE
09/08/2005 Initial vendor notification
09/09/2005 Initial vendor response
10/24/2005 Public disclosure
iDEFENSE Labs is credited with the discovery of this vulnerability.
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X. LEGAL NOTICES
Copyright (c) 2005 iDEFENSE, 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
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