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Security Advisory                                                       CERT-NL
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Author/Source : CERT-NL (Erik-Jan Bos)                      Index  :    S-93-25
Distribution  : Kernel                                      Page   :          1
Classification: External                                    Version:      Final
Subject       : SunOS/Solbourne loadmodule and modload Vulnerability
                                                            Date   :  16-Dec-93
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CERT-NL 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 ftp.nic.surfnet.nl [192.87.46.3]
in the surfnet/net-security/cert-nl/patches/sun-fixes directory.

Solbourne has announced a workaround that is included below.

Please note that this advisory supersedes CERT Coordination Center
Advisory CA-91:22 "SunOS OpenWindows Vulnerability". This Advisory was
not issued by CERT-NL.

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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.

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CERT-NL wishes to thank the CERT Coordination Center and Sun
Microsystems, Inc. and Solbourne Computers, Inc. for their support in
responding to this problem and distributing the necessary information and
patches.
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CERT-NL is the Computer Emergency Response Team, located in The
Netherlands. CERT-NL is a Full Member of the Forum of Incident Response
and Security Teams (FIRST). The constituency of CERT-NL are the SURFnet
connected institutions.

Past CERT-NL Security Bulletins and other CERT-NL related material can
be found on the anonymous FTP server of SURFnet bv:
"ftp.nic.surfnet.nl" [192.87.46.3], in the directory
"surfnet/net-security/cert-nl/docs/bulletin".  This information is also
available using email. Send an email saying "help" to
"mailserv@nic.surfnet.nl".

In case of computer or network security problems please contact CERT-NL
or the CERT of your own constituency. Please be aware of the fact that
we are one (when DST is in effect two) hour(s) ahead of Universal Time
Coordinated (i.e. UTC+0100 (UTC+0200)).
Email:     cert-nl@surfnet.nl
Phone:     +31 30 310290
Fax:       +31 30 340903
Snailmail: SURFnet bv
           Attn. CERT-NL
           P.O. Box 19035
           NL - 3501 DA  UTRECHT
           The Netherlands
A 7 * 24 hours phone number is available to SURFnet SSC's and FIRST
members on request.
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