-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

===============================================================================
>>                                                      CERT-NL, 01-Mar-2000 <<
>> All CERT-NL information has been moved to http://cert.surfnet.nl.  Links  <<
>> to CERT-NL information contained in this advisory are therefore outdated. <<
>>                                                                           <<
>> CERT-NL also has stopped the CERT-CC-Mirror service.  Due to this the     <<
>> links to the CERT-CC mirror are obsolete. Visit the CERT-CC site for the  <<
>> complete CERT-CC advisory texts:                     http://www.cert.org  <<
===============================================================================


===============================================================================
Security Advisory                                                       CERT-NL
===============================================================================
Author/Source : Gert Meijerink                              Index  :    S-96-28
Distribution  : World                                       Page   :          1
Classification: External                                    Version:          1
Subject       : Vendor Initiated Bulletin: FreeBSD man page Date   :  23-may-96
===============================================================================

By courtesy of FreeBSD, Inc. we received information on a vulnerability in the 
man page utility.

CERT-NL recommends to implement the provided workaround.


==============================================================================

=============================================================================
FreeBSD-SA-96:11              Security Advisory
Revised: Wed May 22 00:11:46 PDT 1996              FreeBSD, Inc.

Topic:    security compromise from man page utility

Category:  core
Module:    man
Announced:  1996-05-21
Affects:  FreeBSD 2.0, 2.0.5, 2.1, 2.1-stable, and 2.2-current
Corrected:  2.1-stable and 2.2-current as of 1996-05-21
FreeBSD only:  yes

Patches:  ftp://freebsd.org/pub/CERT/patches/SA-96:11/

=============================================================================

I.   Background

     FreeBSD replaced the standard BSD manual page reader with
     code developed by a third party to support compressed manual
     pages.  A bug was found in the manual page reader which can
     allow an unprivileged local user to compromise system security
     in a limited fashion.  This problem is present in all source
     code and binary distributions of FreeBSD version 2.x released
     before 1996-05-21.


II.  Problem Description

     The man program is setuid to the "man" user.  By executing a
     particular sequence of commands, an unprivileged local user
     may gain the access privileges of the "man" user.  However,
     root access could be obtained with further work.


III. Impact

     The "man" user has no particular special privileges, it is
     the owner of the /usr/share/man/cat[0-9] directory hierarchy.
     Unformatted system manual pages are owned by the "bin" user.
     However, further exploits once "man" is obtained could
     possibly allow a local user to obtain unlimited access via
     a trojan horse.

     This vulnerability can only be exploited by users with a valid
     account on the local system.


IV. Workaround

     One may simply disable the setuid bit on the /usr/bin/man file.
     This will disable caching of formatted manual pages, no system
     functionality will be lost.  This workaround will suffice for
     all versions of FreeBSD affected by this problem.

     As root, execute the command:

   # chmod u-s /usr/bin/man

     then verify that the setuid permissions of the files have been
     removed.  The permissions array should read "-r-xr-xr-x" as
     shown here:

   # ls -l /usr/bin/man
   -r-xr-xr-x  1 man  bin  28672 May 19 20:38 /usr/bin/man

     We also suggest applying the following patch to the source
     distribution so that the man program will not be installed
     setuid man should you rebuild from sources:

    *** /usr/src/gnu/usr.bin/man/man/Makefile  Sun Feb 25 13:39:52 1996
    --- /usr/src/gnu/usr.bin/man/man/Makefile  Wed May 22 00:13:05 1996
    ***************
    *** 1,7 ****
      PROG=  man
      SRCS=  man.c manpath.c glob.c
    - BINMODE=4555
    - BINOWN=  man

      .if exists(${.CURDIR}/../lib/obj)
      LDADD=  -L${.CURDIR}/../lib/obj -lman
    --- 1,5 ----

V. Solution

     The FreeBSD team is in the process of rewriting portions of
     the manual program to avoid this and similar vulnerabilities.
     This security advisory will be updated when a complete solution
     is available.


=============================================================================
FreeBSD, Inc.

Web Site:      http://www.freebsd.org/
Confidential contacts:    security-officer@freebsd.org
PGP Key:      ftp://freebsd.org/pub/CERT/public_key.asc
Security notifications:    security-notifications@freebsd.org
Security public discussion:  security@freebsd.org


==============================================================================
CERT-NL is the Computer Emergency Response Team for SURFnet customers. SURFnet
is the Dutch network for educational, research and related institutes. CERT-NL
is a member of the Forum of Incident Response and Security Teams (FIRST).

All CERT-NL material is available under:
  http://cert.surfnet.nl/

In case of computer or network security problems please contact your local
CERT/security-team or CERT-NL  (if your institute is NOT a SURFnet customer
please address the appropriate (local) CERT/security-team).

CERT-NL is one/two hour(s) ahead of UTC (GMT) in winter/summer,
i.e. UTC+0100 in winter and UTC+0200 in summer (DST).

   Email:     cert-nl@surfnet.nl     ATTENDED REGULARLY ALL DAYS
   Phone:     +31 302 305 305        BUSINESS HOURS ONLY
   Fax:       +31 302 305 329        BUSINESS HOURS ONLY
   Snailmail: SURFnet bv
              Attn. CERT-NL
              P.O. Box 19035
              NL - 3501 DA  UTRECHT
              The Netherlands

NOODGEVALLEN:    06 22 92 35 64      ALTIJD BEREIKBAAR
EMERGENCIES : +31 6 22 92 35 64      ATTENDED AT ALL TIMES
CERT-NL'S EMERGENCY PHONENUMBER IS ONLY TO BE USED IN CASE OF EMERGENCIES:
THE SURFNET HELPDESK OPERATING THE EMERGENCY NUMBER HAS A *FIXED*
PROCEDURE FOR DEALING WITH YOUR ALERT AND WILL IN REGULAR CASES RELAY IT
TO CERT-NL IN AN APPROPRIATE MANNER. CERT-NL WILL THEN CONTACT YOU.
===============================================================================

-----BEGIN PGP SIGNATURE-----
Version: PGP 6.5.1i

iQA/AwUBOL6IKDSYjBqwfc9jEQKMxACdHvTRxOmfoGUjO4APU28gG7qgJhMAoLgk
Eb9Qk6/Xyhtrsgtp9oaVcVV/
=7SGt
-----END PGP SIGNATURE-----