CERT^® Advisory CA-1996-27 Vulnerability in HP Software Installation Programs

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

The text of this advisory was originally released on October 11, 1996, as AA-96.04.Vulnerability.in.HP.Software.Installation.Programs, developed by AUSCERT. 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. Look for it in an "Updates" section at the end of the advisory.

AA-96.04
AUSCERT Advisory

Vulnerability in HP Software Installation Programs
11 October 1996

This vulnerability may allow local users to gain root privileges.

Exploit details involving this vulnerability have been made publicly available.

Vendor patches are being developed, but until they are made available, AUSCERT recommends that sites take the actions suggested in Section 3.

1. Description

The programs supplied with this package create files in an insecure manner. As these programs execute with root privileges, it is possible to create or over-write arbitrary files on the system. The default location of the programs supplied by the package is /usr/sbin.

To determine if you have SD-UX installed on your system, check for the presence of the swinstall (and related) files using the following command:

          % ls -l /usr/sbin/sw*

2. Impact

3. Workarounds/Solution

If software maintenance is required, AUSCERT advises that sites use one of the workarounds given in 3.2, preferably that described in Section 3.2.1.

Vendor patches may also address this vulnerability in the future (Section 3.3).

3.1 Remove permissions

# chmod 400 /usr/sbin/swinstall
# chmod 400 /usr/sbin/swmodify

3.2 Workarounds

The workaround described in 3.2.1 is the preferred method of doing software maintenance. If sites are unable to bring their machines into single user mode, the workaround given in Section 3.2.2 may be more applicable.

3.2.1 Run in single user mode

# chmod 700 /usr/sbin/swinstall
# chmod 700 /usr/sbin/swmodify

          # find /tmp /var/tmp -type l -ok rm {} \;

The execute permissions on the vulnerable programs must be removed before the machine is brought back into multi-user mode.

# chmod 400 /usr/sbin/swinstall
# chmod 400 /usr/sbin/swmodify

3.2.2 Change temporary file environment variable

The SD-UX programs use a number of temporary files. The location of these files can be configured using the environment variable TMPDIR. It is possible to set the environment variable TMPDIR to a non-world writable directory. Having the temporary files created in a non-world writable directory prevents the exploitation of the vulnerability described in this advisory.

NOTE: The environment variable must be set in each login session BEFORE any SD-UX programs are used.

To use this method, the following steps must be taken:

1. As root, create a non-world writable temporary directory for the temporary files used by the SD-UX programs. The location of these temporary files can be configured with the TMPDIR environment variable. In this workaround, we have chosen to use the directory /var/tmp/SD_tmp.
   
   # mkdir /var/tmp/SD_tmp
   # chmod 700 /var/tmp/SD_tmp
   
   For this workaround to be effective, sites should ensure that the parent directory of $TMPDIR has the sticky bit set if the parent directory is world writable. In this workaround, /var/tmp is the directory concerned. The sticky bit on /var/tmp can be set with the command:
   
   # chmod 1777 /var/tmp
   
   In all sessions where software maintenance is performed:

2. Change permissions on the vulnerable programs:

   
   # chmod 700 /usr/sbin/swinstall
   # chmod 700 /usr/sbin/swmodify

3. Set the environment variable TMPDIR:

   
   (under csh)
   # setenv TMPDIR /var/tmp/SD_tmp

   (under sh)
   # TMPDIR=/var/tmp/SD_tmp; export TMPDIR

   
   and verify that the directory exists and is writable by root.
   
   # ls -ld $TMPDIR

4. Perform any software package maintenance.

5. Remove the execute permissions on the vulnerable programs:

   # chmod 400 /usr/sbin/swinstall
   # chmod 400 /usr/sbin/swmodify

6. The environment variable TMPDIR is used by many other programs. You should either exit this interactive session, or reset the TMPDIR environment variables before continuing.

   NOTE: Steps 2) through 6) must be repeated each time software maintenance is performed.

3.3 Install vendor patches

UPDATES

Hewlett-Packard

1) From your Web browser, access the URL:

http://us-support.external.hp.com
(for US,Canada, Asia-Pacific, and Latin-America)

http://europe-support.external.hp.com
(for Europe)

2) On the HP Electronic Support Center main screen, select the hyperlink "Support Information Digests".

3) On the "Welcome to HP's Support Information Digests" screen, under the heading "Register Now", select the appropriate hyperlink "Americas and Asia-Pacific", or "Europe".

4) On the "New User Registration" screen, fill in the fields for the User Information and Password and then select the button labeled "Submit New User".

5) On the "User ID Assigned" screen, select the hyperlink "Support Information Digests".

Note what your assigned user ID and password are for future reference.

6) You should now be on the "HP Support Information Digests Main" screen. You might want to verify that your email address is correct as displayed on the screen. From this screen, you may also view/subscribe to the digests, including the security bulletins digest.

To get a patch matrix of current HP-UX and BLS security patches referenced by either Security Bulletin or Platform/OS, click on following screens in order:

Technical Knowledge Database
Browse Security Bulletins
Security Bulletins Archive
HP-UX Security Patch Matrix

CERT/CC Contact Information

Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:

CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.

CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday through Friday; they are on call for emergencies during other hours, on U.S. holidays, and on weekends.

Using encryption

We strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from

http://www.cert.org/CERT_PGP.key

If you prefer to use DES, please call the CERT hotline for more information.

Getting security information

CERT publications and other security information are available from our web site

http://www.cert.org/

* "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office.

NO WARRANTY
Any material furnished by Carnegie Mellon University and the Software Engineering Institute is furnished on an "as is" basis. Carnegie Mellon University makes no warranties of any kind, either expressed or implied as to any matter including, but not limited to, warranty of fitness for a particular purpose or merchantability, exclusivity or results obtained from use of the material. Carnegie Mellon University does not make any warranty of any kind with respect to freedom from patent, trademark, or copyright infringement.

Copyright 1996 Carnegie Mellon University.

Sep. 24, 1997  Updated copyright statement
July 28, 1997 Updates section - added information from Hewlett-Packard.