14-May-91 -- /Security

    Date: Wed, 15 May 91 11:52:21 +0200
    From: dietrich@cernvax.cern.ch (dietrich wiegandt)
    To: kmsdj@crnvma.cern.ch, myersdr@vxcern.cern.ch, tbl@cernvax.cern.ch
    Subject: FYI

    Path: cernvax!mcsun!uunet!tut.cis.ohio-state.edu!ucbvax!CERT.SEI.CMU.EDU!cert-advisory-request
    From: cert-advisory-request@CERT.SEI.CMU.EDU (CERT Advisory)
    Newsgroups: comp.security.announce
    Subject: CERT Advisory - NeXTstep Vulnerabilities
    Message-ID: <9105141608.AA03956@tictac.cert.sei.cmu.edu>
    Date: 14 May 91 16:06:39 GMT
    Sender: daemon@ucbvax.BERKELEY.EDU
    Distribution: inet
    Organization: The Computer Emergency Response Team
    Lines: 84
    Approved: cert@cert.sei.cmu.edu

    CA-91:06                        CERT Advisory
                                     May 14, 1991
                NeXT rexd, /private/etc, Username me Vulnerabilities

    ---------------------------------------------------------------------------

    The Computer Emergency Response Team/Coordination Center (CERT/CC) and
    NeXT Computer, Inc. have received information concerning three
    vulnerabilities in NeXT computers running various releases (see below)
    of NeXTstep software.  For more information, please contact your
    authorized support center.  If you are an authorized support provider,
    please contact NeXT through your normal channels.

    ---------------------------------------------------------------------------

    Problem 1 DESCRIPTION:  By default, rexd(8C) is enabled in NeXTstep
    versions 2.0 and 2.1.  (Note that no NeXT software uses rexd.)

    Problem 1 IMPACT:  Leaving rexd enabled allows remote users to execute
    processes on a NeXT computer.

    Problem 1 SOLUTION:  Comment out or remove the rexd line in
    /etc/inetd.conf (unless you're using the remote execution facility),
    and either restart the computer or cause inetd to re-read it's
    configuration file, using:

            kill -HUP <inetd pid>

    Problem 2 DESCRIPTION:  The /private/etc directory is shipped with
    group write permission enabled in all NeXTstep versions through and
    including 2.1.

    Problem 2 IMPACT:  Group write permission in /private/etc enables any
    user in the "wheel" group to modify files in the /private/etc
    directory.

    Problem 2 SOLUTION:  Turn off group write permission for the
    /private/etc directory, using the command:

            chmod g-w /private/etc

    or the equivalent operations from the Workspace Manager's Inspector
    panel.

    Problem 3 DESCRIPTION: Username "me" is a member of the "wheel" group
    in all NeXTstep versions through and including 2.1.

    Problem 3 IMPACT:  Having username "me" in the "wheel" group enables
    "me" to use the su(8) command to become root (the user must still know
    the root password, however).

    Problem 3 SOLUTION:  Unless you have specific reason(s) not to, remove
    the user "me" from the wheel group.

    ---------------------------------------------------------------------------

    The CERT/CC would like to thank NeXT Computer, Inc. for their response
    to this vulnerability.  CERT/CC would also like to thank Fuat Baran
    for his technical assistance.

    ---------------------------------------------------------------------------

    If you believe that your system has been compromised, contact CERT/CC
    via telephone or e-mail.

    Computer Emergency Response Team/Coordination Center (CERT/CC)
    Software Engineering Institute
    Carnegie Mellon University
    Pittsburgh, PA 15213-3890

    Internet E-mail: cert@cert.sei.cmu.edu
    Telephone: 412-268-7090 24-hour hotline:
               CERT/CC personnel answer 7:30a.m.-6:00p.m. EST,
               on call for emergencies during other hours.

    Past advisories and other computer security related information are
    available for anonymous ftp from the cert.sei.cmu.edu (128.237.253.5)
    system.