Vulnerability in Solaris admintool

Original issue date: August 5, 1996
Last revised: October 20, 1997
Vendor information for Sun has been added to the UPDATES section.

A complete revision history is at the end of this file.

The text of this advisory was originally released on July 30, 1996, as AUSCERT Advisory AL-96.03, developed by the Australian Computer Emergency Response Team. Because of the seriousness of the problem, we are reprinting the AUSCERT advisory here with their permission. Only the contact information at the end has changed: AUSCERT contact information has been replaced with CERT/CC contact information.

We will update this advisory as we receive additional information. Please check advisory files regularly for updates that relate to your site.


AUSCERT has received a report of a vulnerability in the Sun Microsystems Solaris 2.x distribution involving the program admintool. This program is used to provide a graphical user interface to numerous system administration tasks.

This vulnerability may allow a local user to gain root privileges.

Exploit details involving this vulnerability have been made publicly available.

At this stage, AUSCERT is not aware of any official patches. AUSCERT recommends that sites take the actions suggested in Section 3 until official patches are available.


1. Description

admintool is a graphical user interface that enables an administrator to perform several system administration tasks on a system. These tasks include the ability to manage users, groups, hosts and other services.

To help prevent different users updating system files simultaneously, admintool uses temporary files as a locking mechanism. The handling of these temporary files is not performed in a secure manner, and hence it may be possible to manipulate admintool into creating or writing to arbitrary files on the system. These files are accessed with the effective uid of the process executing admintool.

In Solaris 2.5, admintool is set-user-id root by default. That is, all file accesses are performed with the effective uid of root. An effect of this is that the vulnerability will allow access to any file on the system. If the vulnerability is exploited to try and create a file that already exists, the contents of that file will be deleted. If the file does not exist, it will be created with root ownership and be world writable.

In earlier versions of Solaris 2.x, admintool is not set-user-id root by default. In this case, admintool runs only with the privileges of the user executing it. However, local users may wait for a specific user to execute admintool, exploiting the vulnerability to create or write files with that specific users' privileges. Again, files created in this manner will be world writable.

2. Impact

A local user may be able to create or write to arbitrary files on the system. This can be leveraged to gain root privileges.

3. Workarounds/Solution

Currently, AUSCERT is not aware of any official patches which address this vulnerability. When official patches are made available, AUSCERT suggests that they be installed.

Until official patches are available sites are encouraged to completely prevent execution of admintool by any user (including root).

        # chmod 400 /usr/bin/admintool
        # ls -l /usr/bin/admintool
        -r--------   1 root  sys  303516 Oct 27  1995 /usr/bin/admintool

Note that if only the setuid permissions are removed, it is still possible for users to gain privileges when admintool is executed as root.

AUSCERT recommends that, where possible, admintool should not be used at all until official patches are available. In the interim, system administrators should perform administration tasks by using the command line equivalents. More details on performing these tasks may be found in the Sun documentation set.


AUSCERT wishes to thank Brian Meilak (QUT), Marek Krawus (UQ), Leif Hedstrom, Kim Holburn and Michael James for their assistance in this matter.


UPDATES

Vendor Information

Below is information we have received from vendors. If you do not see your vendor's name below, contact the vendor directly for information.

Sun Microsystems, Inc.

Sun Microsystems has provided the following list of patches in response to this advisory:
103558-10 5.5.1
103559-07 5.5.1_x86
103247-07 5.5
103245-08 5.5_x86

Copyright 1996 Carnegie Mellon University.


Revision History
Oct. 20, 1997  Vendor information for Sun has been added to the UPDATES
                 section.
Sep. 24, 1997  Updated copyright statement
Aug. 30, 1996  Removed references to CA-96.16.README.
               Beginning of the advisory - removed AUSCERT advisory header
                 to avoid confusion.