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             The Computer Incident Advisory Capability
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                         Information Bulletin

March 28, 1991, 1200 PST                                     Number B-21

      Patch Available for SunOS 4.0.3 in.telnetd and in.rlogind

________________________________________________________________________
PROBLEM:   SunOS versions 4.0.3 in.telnetd and in.rlogind may send
  output to an unauthorized user.  
PLATFORM: All Sun3 and Sun4 computers running SunOS 4.0.3.  
DAMAGE:  May allow unauthorized access to the system.  
SOLUTIONS:  Patch/update available from Sun as patch file
  100125-03.tar.Z 
IMPACT OF PATCH:  Vulnerability eliminated.  No other side-effects
  reported.  Critical Information about in.telnetd and in.rlogind Patch
________________________________________________________________________
     Critical Information about in.telnetd and in.rlogind Patch

CIAC information bulletin B-20 describes a problem with in.telnetd on
Sun 3 and Sun 4 computers.   The current bulletin contains a correction
to part of the information in the previous bulletin concerning the
applicability and installation of a patch for Sun OS 4.0.3 systems.
Bulletin B-21 also provides information on an additional patch for a
similar problem with in.rlogind in Sun OS 4.0.3 systems.

Sun OS 4.1 or 4.1.1 systems are subject to the problem with in.telnetd
but not to the problem with in.rlogind.   For these systems, in.telnetd
should be patched using the procedures listed in bulletin B-20.

The Sun Microsystems patch described in bulletin B-20 may not work on
some SunOS 4.0.3 systems.  This vendor has, therefore, created a fix
for the in.telnetd and in.logind utilities to patch SunOS 4.0.3
systems.  If not patched, these utilities may allow unauthorized access
to systems.  The patch is available from Sun Microsystems as the
updated Patch ID# 100125-03 (this number is required to order this
patch from the Sun Answer Center).  This patch is also available via
anonymous ftp at uunet.uu.net (IP# 192.48.96.2) in the file
sun-dist/100125-03.tar.Z.  This patch file does not contain
installation instructions.  We recommend the following installation
procedures, which supersede the procedures listed in bulletin B-20 for
Sun OS 4.0.3 systems:

1.  Log in as root on the system to be repaired.

2.      Disable the flawed version of in.telnetd and in.rlogind with
the following commands:

  # mv /usr/etc/in.telnetd /usr/etc/in.telnetd.FCS
  # mv /usr/etc/in.rlogind /usr/etc/in.rlogind.FCS
  # chmod 600 /usr/etc/in.telnetd.FCS /usr/etc/in.rlogind.FCS

3.      Obtain the patch file 100125-03.tar.Z (either from Sun or a
trusted anonymous FTP site such as uunet.uu.net).

4.  Uncompress the patch file:

  # uncompress 100125-03.tar.Z

5.      Extract the patch file appropriate to your architecture (either
sun3, sun3x, sun4, or sun4c -- contact your Sun representative if you
do not know which architecture you have) and your operating system
level (either 4.0.3 or 4.0.3c)

  # tar xf 100125-03.tar {architecture}/4.0.3/in.telnetd
  # tar xf 100125-03.tar {architecture}/4.0.3/in.rlogind
  where {architecture} is one of sun3, sun3x, sun4, or sun4c*.

6.      Copy the patch file to the appropriate directory, and set the
ownership and permissions of the utility:

  # cp {architecture}/4.0.3/in.telnetd /usr/etc/in.telnetd
  # cp {architecture}/4.0.3/in.rlogind /usr/etc/in.rlogind
  # chown root.staff /usr/etc/in.telnetd /usr/etc/in.rlogind
  # chmod 711 /usr/etc/in.telnetd /usr/etc/in.rlogind

7.  Kill any existing telnet and rlogin processes that may be running.

  # ps gax | grep in.telnetd
  # ps gax | grep in.rlogind
  # kill -9 ####
  where #### is the number of each in.telnetd process found in
  the previous ps commands.  Please note that this command may
  disrupt ongoing sessions of users attempting to use the
  system.  As an alternative to this step, you may consider
  rebooting the computer, allowing time for all current users to
  log out.

Once you have verified that the new version of telnet is operational,
it is advisable to delete the unpatched version of the utilities
/usr/etc/in.telnetd.FCS and /usr/etc/in.rlogind.FCS to prevent their
unauthorized use.

 For additional information or assistance, please contact CIAC:   
 
  Tom Longstaff
  (415) 423-4416 or (FTS) 543-4416

  During working hours call CIAC at (415) 422-8193 or (FTS)
  532-8193 or send e-mail to ciac@cheetah.llnl.gov. 

  Send FAX messages to:  (415) 423-0913 or (FTS) 543-0913.
_____
   * - Note that for Sun4c systems, the correct file is 
       sun4c/4.0.3c/in.telnetd and sun4c/4/0/3c/in.rlogind

CERT/CC provided some of the information used in this bulletin.  This
document was prepared as an account of work sponsored by an agency of
the United States Government. Neither the United States Government nor
the University of California nor any of their employees, makes any
warranty, express or implied, or assumes any legal liability or
responsibility for the accuracy, completeness, or usefulness of any
information, apparatus, product, or process disclosed, or represents
that its use would not infringe privately owned rights. Reference
herein to any specific commercial products, process, or service by
trade name, trademark, manufacturer, or otherwise, does not necessarily
constitute or imply its endorsement, recommendation or favoring by the
United States Government or the University of California. The views and
opinions of authors expressed herein do not necessarily state or
reflect those of the United States Government or the University of
California, and shall not be used for advertising or product
endorsement purposes.