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CERT* Vendor-Initiated Bulletin VB-98.04
April 27, 1998

Topic: Vulnerabilities in xterm and Xaw 
Source: The Open Group 

To aid in the wide distribution of essential security information, the
CERT Coordination Center is forwarding the following information from
The Open Group. The Open Group urges you to act on this information as
soon as possible. Further questions about these vulnerabilities should
be directed to your vendor or support personnel.


=======================FORWARDED TEXT STARTS HERE============================
______________________________________________________________________________
             The Open Group X Project Team Security Advisory

        Title:   xterm and Xaw library vulnerability
        Date:    April 27, 1998
______________________________________________________________________________

The Open Group X Project Team provides this information freely to the X11 
user community for its consideration, interpretation, implementation and use.
The Open Group X Project Team recommends that this information be acted upon 
as soon as possible.

The Open Group X Project Team provides the information in this Security 
Advisory on an "AS-IS" basis only, and disclaims all warranties with respect 
thereto, express, implied or otherwise, including, without limitation, any 
warranty of merchantability or fitness for a particular purpose.  In no event 
shall The Open Group be liable for any loss of profits, loss of business, loss
of data or for any indirect, special, exemplary, incidental or consequential
damages of any kind arising from your use of, failure to use or improper
use of any of the instructions or information in this Security Advisory.
______________________________________________________________________________


I. Description

Vulnerabilities exist in the terminal emulator xterm(1), and the Xaw
library distributed in various MIT X Consortium; X Consortium, Inc.;
and The Open Group X Project Team releases. These vulnerabilities may
be exploited by an intruder to gain root access. 

The resources and the releases affected by the xterm vulnerability are:

                              Resources
                 inputMethod       preeditType      *Keymap
    Release      
    X11R3           NO                 NO             YES
    X11R4           NO                 NO             YES
    X11R5           NO                 NO             YES
    X11R6           NO                 NO             YES
    X11R6.1         YES                YES            YES
    X11R6.2         YES                YES            YES
    X11R6.3         YES                YES            YES
    X11R6.4         YES                YES            YES

The resources and the releases affected by the Xaw library
vulnerability are

                              Resources
                 inputMethod       preeditType
    Release      
    X11R6           YES                YES
    X11R6.1         YES                YES
    X11R6.2         YES                YES
    X11R6.3         YES                YES
    X11R6.4         YES                YES


(X11R6.2 was not released to the public.)

The Open Group X Project Team has investigated the issue and recommends 
the following steps for neutralizing the exposure. It is HIGHLY RECOMMENDED
that these measures be implemented on ALL vulnerable systems. This issue 
will be corrected in future X Project Team releases of X11.


- - - --------------
- - - --- Impact ---
- - - --------------

By crafting an arbitrarily long string that contains embedded machine code 
and using it to set specific "resources", a user may obtain a shell prompt 
that has root privileges.

Anyone using the MIT X Consortium; X Consortium, Inc.; or X Project Team
xterm and that has xterm installed setuid-root may be vulnerable.

Anyone using an xterm based on any of the sources listed above may
also be vulnerable to the xterm vulnerability.

In order to be vulnerable to the Xaw library vulnerability, the Xaw
Text widget must be used by a setuid-root program. Anyone using an
Xaw replacement based on any of the released versions of Xaw listed
above (e.g. Xaw3d) may also be vulnerable to the Xaw vulnerability.


- - - --------------------------
- - - --- Temporary Solution  ---
- - - --------------------------

     1) Become the root user on the system.

                % /bin/su -
                Password:
                #

     2) Remove the setuid-root bit from the xterm binary.

                # chmod 0755 <path-to-xterm>/xterm


For the Xaw vulnerability, remove the suid-root bit from any programs
which use the Xaw text widget. 

 2) Remove the setuid-root bit from the binary.

                # chmod 0755 <setuid-root-program>


- - - ----------------
- - - --- Solution ---
- - - ----------------

Patches to address this vulnerability have been given to X Project Team 
members: 

    Astec
    Attachmate
    BARCO Chromatics
    CliniComp International
    Digital
    Hewlett-Packard
    Hitachi
    Hummingbird Communications
    IBM
    Jupiter Systems
    Metro Link
    Network Computing Devices
    NetManage
    Peritek
    Seaweed Systems
    Sequent Computer Systems
    Shiman Associates
    Silicon Graphics
    Societe Axel
    Siemens Nixdorf
    Starnet
    SunSoft
    WRQ
    Xi Graphics

The X Project Team periodically makes public patches available to fix a
variety of problems. Announcements about the availability of these patches 
is announced on the Usenet comp.windows.x.announce newsgroup. The patches,
when they become available, may be found on ftp://ftp.x.org/pub/R6.4/fixes/.
The X Project Team only supplies patches for the latest release -- we do 
not make patches for prior releases.

Information on joining The Open Group can be found at 

  http://www.opengroup.org/howtojoin.htm

========================FORWARDED TEXT ENDS HERE=============================

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). See http://www.first.org/team-info/.  

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://ftp.cert.org/pub/CERT_PGP.key


CERT Contact Information
- ------------------------
Email    cert@cert.org

Phone    +1 412-268-7090 (24-hour hotline)
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Fax      +1 412-268-6989

Postal address
        CERT Coordination Center
        Software Engineering Institute
        Carnegie Mellon University
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        USA

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In the subject line, type 
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* Registered U.S. Patent and Trademark Office.

The CERT Coordination Center is part of the Software Engineering
Institute (SEI). The SEI is sponsored by the U. S. Department of Defense.


This file: ftp://ftp.cert.org/pub/cert_bulletins/VB-98.04.xterm.Xaw


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