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EMERGENCY RESPONSE SERVICE
SECURITY VULNERABILITY ALERT
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
root.
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
command:
instfix -ik IX71464
Or run the following command:
lslpp -h bos.net.tcp.client
Your version of bos.net.tcp.client should be 4.1.5.14 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
command:
instfix -ik IX70815
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.
To Order
--------
APARs may be ordered using Electronic Fix Distribution (via FixDist) or
from the IBM Support Center. For more information on FixDist, reference
URL:
http://service.software.ibm.com/aixsupport/
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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