Title: IBM AIX ftp client Vulnerability
Date Issued: October 29, 1997
Last Modified: October 29, 1997
Code: I-012
Source: CIAC
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             __________________________________________________________

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

                             INFORMATION BULLETIN

                        IBM AIX ftp client Vulnerability

October 29, 1997 22:00 GMT                                        Number I-012
______________________________________________________________________________
PROBLEM:       The ftp client can be tricked into running arbitrary commands
               supplied by the remote server.
PLATFORM:      IBM AIX(r) 3.2, 4.1, 4.2
DAMAGE:        Remote ftp servers can cause arbitrary commands to run on the
               local machine. This can include remote root access.
SOLUTION:      Remove the setuid bit from the "ftp" command or apply one of
               the fixes below.
______________________________________________________________________________
VULNERABILITY  The information on this vulnerability should be acted upon as
ASSESSMENT:    soon as possible to avoid possible unauthorized access.
______________________________________________________________________________

[ Start IBM Advisory ]


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                           EMERGENCY RESPONSE SERVICE
                          SECURITY VULNERABILITY ALERT

29 October 1997 19:00 GMT                       Number: ERS-SVA-E01-1997:009.1
==============================================================================
                           VULNERABILITY SUMMARY

VULNERABILITY:    The AIX ftp client interprets server provided filenames

PLATFORMS:        IBM AIX(r) 3.2, 4.1, 4.2

SOLUTION:         Remove the setuid bit from the "ftp" command.

THREAT:           Remote ftp servers can cause arbitrary commands to run on
                  the local machine.

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

I.  Description

The ftp client can be tricked into running arbitrary commands supplied by the
remote server.  When the remote file begins with a pipe symbol, the ftp client
will process the contents of the remote file as a shell script.

II.  Impact

Remote ftp servers can cause arbitrary commands to run on the local machine.
This can include remote root access.

III.  Solutions

  AIX 3.2
  -------
    There are no fixes available for AIX 3.2.  It is suggested that customers
    upgrade to a higher level.

  AIX 4.1
  -------
    Apply the following fix to your system:

        APAR - IX70885

    To determine if you have this APAR on your system, run the following
    command:

       instfix -ik IX70885

    Or run the following command:
   
       lslpp -h bos.net.tcp.client

    Your version of bos.net.tcp.client should be 4.1.5.13 or later.

  AIX 4.2
  -------
    Apply the following fix to your system:

        APAR - IX70886

    To determine if you have this APAR on your system, run the following
    command:

       instfix -ik IX70886

    Or run the following command:
   
       lslpp -h bos.net.tcp.client

    Your version of bos.net.tcp.client should be 4.2.1.10 or later.

IV.  Contact Information

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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Visit the site for information about the service, copies of security alerts,
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IBM-ERS uses Pretty Good Privacy* (PGP*) as the digital signature mechanism
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"Pretty Good Privacy" and "PGP" are trademarks of Philip Zimmermann.

IBM-ERS is a Member Team of the Forum of Incident Response and Security Teams
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Copyright 1997 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
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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,
in its entirety only, by any person provided such reproduction and/or
distribution is performed for non-commercial purposes and with the intent of
increasing the awareness of the Internet community.


[ End IBM Advisory ]

______________________________________________________________________________

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


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