AUSCERT External Security Bulletin Redistribution

               ESB-97.142 -- IBM security vulnerability alert
        The AIX "nslookup" command does not drop privileges correctly
                               30 October 1997


IBM's Internet Emergency Response Service has released the following
advisory concerning a vulnerability in the nslookup command under IBM
AIX(r) 4.1 and 4.2.  This vulnerability may allow local users to gain root

The following security bulletin is provided as a service to AUSCERT's
members.  As AUSCERT did not write this document, AUSCERT has had no
control over its content.  As such, the decision to use any or all of this
information is the responsibility of each user or organisation, and should
be done so in accordance with site policies and procedures.

Contact information for IBM-ERS is included in the Security Bulletin below.
If you have any questions or need further information, please contact them

Previous advisories and external security bulletins can be retrieved from:


If you believe that your system has been compromised, contact AUSCERT or your
representative in FIRST (Forum of Incident Response and Security Teams).

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 4477
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
	AUSCERT personnel answer during Queensland business hours
	which are GMT+10:00 (AEST).
	On call after hours for emergencies.

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                           EMERGENCY RESPONSE SERVICE

29 October 1997 19:00 GMT                        Number: ERS-SVA-E01-1997:008.1
                           VULNERABILITY SUMMARY

VULNERABILITY:    The AIX "nslookup" command does not drop privileges correctly

PLATFORMS:        IBM AIX(r) 4.1, 4.2

SOLUTION:         Apply the fixes listed below

THREAT:           Local users can become root

                           DETAILED INFORMATION

I.  Description

The nslookup command has a vulnerability that allows local users to become

II.  Solutions

  A.  How to alleviate the problem

      This problem can be alleviated by removing the set-user-id bit from the
      "nslookup" program.  To do this, execute the following command as "root":

          chmod 555 /usr/bin/nslookup

      Removing the set-user-id bit will not result in lost functionality unless
      /etc/resolv.conf exists and is not world-readable.

  B.  Official fix

      AIX 4.1
      Apply the following fix to your system:

        APAR - IX71464

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

        instfix -ik IX71464

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

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

      AIX 4.2
      Apply the following fix to your system:

        APAR - IX70815

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

        instfix -ik IX70815

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

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

      To Order
      APARs may be ordered using Electronic Fix Distribution (via FixDist) or
      from the IBM Support Center.  For more information on FixDist, reference


      or send e-mail to aixserv@austin.ibm.com with a subject of "FixDist".

III.  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.


IBM's Internet Emergency Response Service (IBM-ERS) is a subscription-based
Internet security response service that includes computer security incident
response and management, regular electronic verification of your Internet
gateway(s), and security vulnerability alerts similar to this one that are
tailored to your specific computing environment.  By acting as an extension
of your own internal security staff, IBM-ERS's team of Internet security
experts helps you quickly detect and respond to attacks and exposures across
your Internet connection(s).

As a part of IBM's Business Recovery Services organization, the IBM Internet
Emergency Response Service is a component of IBM's SecureWay(tm) line of
security products and services.  From hardware to software to consulting,
SecureWay solutions can give you the assurance and expertise you need to
protect your valuable business resources.  To find out more about the IBM
Internet Emergency Response Service, send an electronic mail message to
ers-sales@vnet.ibm.com, or call 1-800-742-2493 (Prompt 4).

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,
team contact information, and other items.

IBM-ERS uses Pretty Good Privacy* (PGP*) as the digital signature mechanism for
security vulnerability alerts and other distributed information.  The IBM-ERS
PGP* public key is available from http://www.ers.ibm.com/team-info/pgpkey.html.
"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
(FIRST), a global organization established to foster cooperation and response
coordination among computer security teams worldwide.

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
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 contained herein, or
represents that its use would not infringe any 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 IBM or
its subsidiaries.  The views and opinions of authors expressed herein do not
necessarily state or reflect those of IBM or its subsidiaries, and may not be
used for advertising or product endorsement purposes.

The material in this security alert may be reproduced and distributed,
without permission, in whole or in part, by other security incident response
teams (both commercial and non-commercial), provided the above copyright is
kept intact and due credit is given to IBM-ERS.

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.


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