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CA-93:03                         CERT Advisory
                              February 3, 1993
                      SunOS File/Directory Permissions
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The default permissions on a number of files and directories in SunOS
4.1, 4.1.1, 4.1.2, and 4.1.3 are set incorrectly.  These problems are
relevant for the sun3, sun3x, sun4, sun4c, and sun4m architectures.
They have been fixed in SunOS 5.0.  (Note that SunOS 5.0 is the operating
system included in the Solaris 2.0 software distribution.)

An updated patch to reset these permissions is available from Sun.
CERT has seen an increasing number of attackers exploit these problems
on systems and we encourage sites to consider installing this patch.

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I.   Description

    File permissions on numerous files were set incorrectly in the
    distribution tape of 4.1.x.  A typical example is that a file which
    should have been owned by "root" was set to be owned by "bin".

    Not all sites will need or want to install the patch for this problem.
    The decision of what user id should own most system files and
    directories depends on the administrative practices of the site.
    It is quite reasonable to run a system where the majority
    of files are owned by "bin" as long as the entire system is run in
    a manner consistent with that practice.  As distributed, the SunOS
    configuration expects most system files to be owned by "root".
    The fact that some are not creates security problems.

    Therefore, sites that are running the SunOS versions listed above
    as distributed should install the patch described below.
    Sites that have made an informed choice to configure their system
    differently may instead want to review the patch script and
    consider which, if any, of the changes should be made on their system.

II.  Impact

    Depending on the specific configuration of the local site,
    the default permissions may allow local users to gain "root" access.

III. Solution

    1) Sun has provided a script to reset file and directory permissions
       to their correct values.  The script is available in Sun's
       Patch #100103 version 11.  This patch can be obtained via
       local Sun Answer Centers worldwide as well as through
       anonymous FTP from the ftp.uu.net (137.39.1.9) system
       in the /systems/sun/sun-dist directory.

             Patch ID     Filename             Checksum
             100103-11    100103-11.tar.Z      19847   6

       Please note that Sun Microsystems sometimes updates patch files.
       If you find that the checksum is different please contact
       Sun Microsystems or CERT for verification.

    2) Uncompress the file, extract the contents of the tar archive,
       and review the README file.

            % uncompress 100103-11.tar.Z
            % tar xfv 100103-11.tar
            % cat README

    3) This patch will reset the group ownership of certain files to
       either "staff" or "bin".  Make sure you have entries in
       the "/etc/group" file for these accounts.

            % grep '^staff:' /etc/group
            % grep '^bin:' /etc/group

       If you do not have both of these you will need to either add the
       missing account(s) or modify the patch script (4.1secure.sh)
       to reflect group ownerships appropriate for your site.
       (Note that the security problems are fixed by the ownerships and
       mode bits specified in the patch - not by the group ownerships.
       Therefore, changing the group ownerships does not invalidate
       the patch.)

    4) As "root", run the patch script.

             # sh 4.1secure.sh

       This patch fixes Sun BugId's 1046817, 1047044, 1048142, 1054480,
       1037153, 1039292, and 1042662.

    5) The patch script will set "/usr/kvm/crash" to mode 02700 owned
       by "root".  While this is not insecure, since only "root" can run
       the program, CERT recommends that the setgid bit be removed to
       prevent abuse if world execute permission were to be added
       some time later.

       As "root", make "/usr/kvm/crash" not a set-group-id program.

            # chmod 755 /usr/kvm/crash

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

Internet E-mail: [email protected]
Telephone: 412-268-7090 (24-hour hotline)
          CERT personnel answer 7:30 a.m.-6:00 p.m. EST(GMT-5)/EDT(GMT-4),
          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 cert.org (192.88.209.5).


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