CERT Advisory - SunOS/Solbourne loadmodule and modload Vulnerability

CERT Advisory cert-advisory-request at cert.org
Wed Dec 15 20:08:44 UTC 1993

CA-93:18                         CERT Advisory
                               December 15, 1993
                SunOS/Solbourne loadmodule and modload Vulnerability

The CERT Coordination Center has received information concerning a 
vulnerability in /usr/etc/modload and $OPENWINHOME/bin/loadmodule in Sun
Microsystems, Inc. SunOS 4.1.1, 4.1.2, 4.1.3, and 4.1.3c and OpenWindows 3.0
on all sun4 and Solbourne Computer, Inc. architectures.  The problem does not
exist in Solaris 2.x, Solaris x86, and sun3 architectures (OpenWindows 3.0
was not released for the sun3 architecture).

Sun has produced a patch for these vulnerabilities for sun4 architectures.
It is available through your local Sun Answer Center as well as through
anonymous FTP from the ftp.uu.net system in the /systems/sun/sun-dist
directory or from the ftp.eu.net system in the /sun/fixes directory.

Solbourne has announced a workaround that is included below.

Please note that this advisory supersedes CERT Advisory CA-91:22 "SunOS
OpenWindows Vulnerability".


I.   Description

     loadmodule(8) and modload(8) can be exploited to execute a user's 
     program using the effective UID of root.

II.  Impact

     This vulnerability allows a local user to gain root access.

III. Solution

     A. SunOS Solution

     Obtain and install the appropriate patches according to the 
     instructions included with the patches.

     Module           Patch ID        Filename
     ----------       ---------       ---------------
     loadmodule       100448-02       100448-02.tar.Z

                  BSD Checksum = 19410 5
                  MD5 Checksum = 0215910cf65e055ed3042070bd961a22

     modload          101200-02       101200-02.tar.Z

                  BSD Checksum = 41677 28
                  MD5 Checksum = 626ab2917204eb6e6eb5f165cca3e908

     B. Solbourne Solution

     Solbourne systems do not support the "loadmodule" functionality.
     This vulnerability can be fixed on Solbourne systems by removing
     the setuid bit:

        chmod 0755 /usr/openwin/bin/loadmodule

     The modload program does not need to replaced or changed.

The CERT Coordination Center wishes to thank Sun Microsystems, Inc.
and Solbourne Computers, Inc. for their support in responding to this

If you believe that your system has been compromised, contact the CERT
Coordination Center or your representative in Forum of Incident
Response and Security Teams (FIRST).

Internet E-mail: cert at cert.org
Telephone: 412-268-7090 (24-hour hotline)
           CERT personnel answer 8:30 a.m.-5:00 p.m. EST(GMT-5)/EDT(GMT-4),
           and are on call for emergencies during other hours.

CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh, PA 15213-3890

Past advisories, information about FIRST representatives, and other
information related to computer security are available for anonymous 
FTP from info.cert.org.

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