-----BEGIN PGP SIGNED MESSAGE----- ============================================================================= CERT(sm) Advisory CA-96.27 Original issue date: December 19, 1996 Last revised: --- Topic: Vulnerability in HP Software Installation Programs - ----------------------------------------------------------------------------- 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 Last Revised: - ---------------------------------------------------------------------------- AUSCERT has received information that there is a vulnerability in the Hewlett Packard Software Distributor product, SD-UX, used to install, update, remove and package HP-UX software and patches. This software is installed by default under HP-UX 10.x and may have been specifically installed as additional software under HP-UX 9.x. Any system with the SD-UX package installed is vulnerable. 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 HP Software Distributor (SD-UX) is a package that provides a user interface which can be used to install, update, remove, and package HP-UX software and patches. 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* Individual sites are encouraged to check their systems for the SD-UX package, and if installed, take the actions recommended in Section 3. 2. Impact Local users may be able to create or over-write arbitrary files on the system. This can be leveraged to gain root privileges. 3. Workarounds/Solution AUSCERT recommends that sites prevent possible exploitation of this vulnerability by taking the measures stated in Section 3.1 immediately. 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 Until official patches are available sites are encouraged to completely prevent the execution of all vulnerable SD-UX programs by any user (including root). # chmod 400 /usr/sbin/swinstall # chmod 400 /usr/sbin/swmodify Note that if only the setuid permissions are removed, it is still possible for users to gain the privileges of any user executing the SD-UX programs (including root). 3.2 Workarounds AUSCERT recommends that if software maintenance is required, sites implement one of the following workarounds until official vendor patches are made available. 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 If packages must be installed, the machine should be brought into single-user mode, execute permissions re-enabled on /usr/sbin/swinstall, # chmod 700 /usr/sbin/swinstall # chmod 700 /usr/sbin/swmodify and all symbolic links in /var/tmp and /tmp removed. The following command can be used to remove the symbolic links: # find /tmp /var/tmp -type l -ok rm {} \; Once this has been completed, any software package maintenance may be safely performed. 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 This workaround should only be used if the SD-UX programs must be used while the machine is in multi-user mode. 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 Official vendor patches are currently being developed to address the vulnerability described in this advisory. When vendor patches are made available, AUSCERT suggests that they be installed. - ---------------------------------------------------------------------------- AUSCERT thanks Information Technology Services of the University of Southern Queensland, Viviani Paz (The University of Queensland) and Hewlett Packard for their assistance in this matter. - ---------------------------------------------------------------------------- If you believe that your system has been compromised, contact the CERT Coordination Center or your representative in the Forum of Incident Response and Security Teams (FIRST). We strongly urge you to encrypt any sensitive information you send by email. The CERT Coordination Center can support a shared DES key and PGP. Contact the CERT staff for more information. Location of CERT PGP key ftp://info.cert.org/pub/CERT_PGP.key CERT Contact Information - ------------------------ Email cert@cert.org Phone +1 412-268-7090 (24-hour hotline) CERT personnel answer 8:30-5:00 p.m. EST (GMT-5)/EDT(GMT-4), and are on call for emergencies during other hours. Fax +1 412-268-6989 Postal address CERT Coordination Center Software Engineering Institute Carnegie Mellon University Pittsburgh PA 15213-3890 USA CERT publications, information about FIRST representatives, and other security-related information are available for anonymous FTP from http://www.cert.org/ ftp://info.cert.org/pub/ CERT advisories and bulletins are also posted on the USENET newsgroup comp.security.announce To be added to our mailing list for CERT advisories and bulletins, send your email address to cert-advisory-request@cert.org CERT is a service mark of Carnegie Mellon University. This file: ftp://info.cert.org/pub/cert_advisories/CA-96.27.hp_sw_install http://www.cert.org click on "CERT Advisories" ============================================================================= UPDATES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Revision history -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBMrlxM3VP+x0t4w7BAQENaAP9FJc1yZVCB/XkEDKNVA7YCT/2jjt0zpUm 2/fyP1x66HJZOS84mLp2cZkxjbdLGost68V8sykhDb3HEfXm8kabddNR5+pGbxNG TQPDrj1wjeEx1rxjWyUI2aBlqY7avzneExM7RncrUuwlQmot4wMYJy5VFbi1eqw7 fI9a/C7vBXE= =DJR0 -----END PGP SIGNATURE-----