From ciac@tholia.llnl.gov Sat Feb 14 15:13:05 1998
From: CIAC Mail User <ciac@tholia.llnl.gov>
To: ciac-bulletin@tholia.llnl.gov
Date: Thu, 12 Feb 1998 13:36:51 -0800 (PST)
Subject: CIAC Bulletin I-029: IBM AIX Telnet Denial-of-Service Vulnerability

[  For Public Release  ]
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             __________________________________________________________

                       The U.S. Department of Energy
                    Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
                          \___  __|__  /   \  \___
             __________________________________________________________

                             INFORMATION BULLETIN

                 IBM AIX Telnet Denial-of-Service Vulnerability

February 11, 1998 19:00 GMT                                       Number I-029
______________________________________________________________________________
PROBLEM:       A vulnerabilty has been identified that causes all tty activity
               to hang and prevents new telnet sessions.
PLATFORM:      IBM AIX(r) 4.1.x, 4.2.x, 4.3
DAMAGE:        Remote users may cause the system to run out of message blocks
               and hang.
SOLUTION:      Apply the fixes listed below.
______________________________________________________________________________
VULNERABILITY  This vulnerability has been posted to the Bugtraq mailing list.
ASSESSMENT:                                                                  
______________________________________________________________________________

[ Start IBM Corporation's Advisory ]


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                           EMERGENCY RESPONSE SERVICE
                          SECURITY VULNERABILITY ALERT

11 February 1998 13:30 GMT                      Number: ERS-SVA-E01-1998:003.1
==============================================================================
                             VULNERABILITY  SUMMARY

VULNERABILITY:  Telnet denial of service attack

PLATFORMS:      IBM AIX(r) 4.1.x, 4.2.x, 4.3

SOLUTION:       Apply the fixes listed below.

THREAT:         Remote users can cause the system to hang.

==============================================================================
                              DETAILED INFORMATION

I.  Description

A denial of service attack has been posted to the Bugtraq mailing list
that causes all tty activity to hang and prevents new telnet sessions
from being established.

II.  Impact

Remote users can cause the system to run out of message blocks and
hang.

III.  Solutions

  A.  Official fix

      At this time, only the AIX 4.1.x APAR is available.  AIX 4.2.x
      and 4.3.0 customers can apply the temporary fix listed below
      until the official APARs are available.  There are no fixes
      planned for AIX 3.2.5 or earlier.  It is recommended that version
      3 customers upgrade to version 4.

      AIX 4.1.x:  IX73427   (bos.rte.tty 4.1.5.20)   -- available now
      AIX 4.2.x:  IX73580
      AIX 4.3.0:  IX73214

  B.  How to alleviate the problem

      A temporary fix is available for AIX 4.2.x and AIX 4.3.0 via
      anonymous ftp from:

        ftp://aix.software.ibm.com/aix/efixes/security/ldterm_fix.tar.Z

      Filename          sum             md5
      ===================================================================
      ldterm.42         52419    77     7ec3ff7eb83ded8f50219a838a0a4c0b
      ldterm.43         37579    77     f066b7d6c3a845c892941a7ab15a6e60
      ldterm_fix.sh     10210     3     e3a8bbecda52ff68391657f008b46262

      Use the following steps (as root) to install the temporary fix:

      1.  Use the following command to determine the version of the
          bos.rte.tty fileset on your machine.

        # lslpp -l bos.rte.tty

          If the version is not at the level described below, install
          the requisite APAR for your release.  This will help ensure
          that the efix binary will run properly.

          Release       bos.rte.tty version       requisite APAR
          =============================================================
          AIX 4.2.x     less than 4.2.1.9         install IX73755
          AIX 4.3.0     less than 4.3.0.3         install IX73397

      2.  Uncompress and extract the fix.

        # uncompress < ldterm_fix.tar.Z | tar xf -
        # cd ldterm_fix

      3.  Run the ldterm_fix.sh script to install the new tty driver.

        # ./ldterm_fix.sh

      4.  Reboot.

      NOTE: This temporary fix has not been fully regression tested.

IV. Obtaining Fixes

IBM AIX APARs may be ordered using Electronic Fix Distribution (via the
FixDist program), or from the IBM Support Center.  For more information
on FixDist, and to obtain fixes via the Internet, please reference

        http://service.software.ibm.com/aixsupport/

or send electronic mail to "aixserv@austin.ibm.com" with the word
"FixDist" in the "Subject:" line.

V.  Acknowledgements

Thanks to Kevin Ruderman <rudi@bu.edu> for bringing this problem to our
attention.

VI.  Contact Information

Comments regarding the content of this announcement can be directed to
the IBM Support Center or to:

   security-alert@austin.ibm.com

To request the PGP public key that can be used to encrypt new AIX
security vulnerabilities, send email to security-alert@austin.ibm.com
with a subject of "get key".

If you would like to subscribe to the AIX security newsletter, send a
note to aixserv@austin.ibm.com with a subject of "subscribe Security".
To cancel your subscription, use a subject of "unsubscribe Security".
To see a list of other available subscriptions, use a subject of
"help".

IBM and AIX are a registered trademark of International Business
Machines Corporation.  All other trademarks are property of their
respective holders.

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

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IBM-ERS maintains a site on the World Wide Web at http://www.ers.ibm.com/.
Visit the site for information about the service, copies of security alerts,
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IBM-ERS is a Member Team of the Forum of Incident Response and Security Teams
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Copyright 1998 International Business Machines Corporation.

The information in this document is provided as a service to customers of
the IBM Emergency Response Service.  Neither International Business Machines
Corporation, Integrated Systems Solutions Corporation, nor any of their
employees, makes any warranty, express or implied, or assumes any legal
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Reference herein to any specific commercial products, process, or service by
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The material in this security alert may be reproduced and distributed,
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This security alert may be reproduced and distributed, without permission,
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distribution is performed for non-commercial purposes and with the intent of
increasing the awareness of the Internet community.


[ End IBM Corporation's Advisory ]

______________________________________________________________________________

CIAC wishes to acknowledge the contributions of IBM Corporation for the
information contained in this bulletin.
______________________________________________________________________________


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