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TUCoPS :: Unix :: Various Flavours :: ciach013.txt

IBM AIX Security Vulnerabilities





             __________________________________________________________

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

                             INFORMATION BULLETIN

          IBM AIX(r) Security Vulnerabilities (gethostbyname, lquerypv)

December 10, 1996 23:00 GMT                                        Number H-13
______________________________________________________________________________
PROBLEM:       Two problems have been identified in IBM AIX: (1) Possible
               buffer overrun condition in "gethostbyname()" library function,
               and (2) the "lquerypv" command does not correctly enforce file
               access permissions.
PLATFORM:      (1) IBM AIX 3.2.x, 4.1.x, 4.2.x, (2) IBM AIX 4.1, 4.2
DAMAGE:        (1) If exploited, this condition may permit unauthorized
               super-user access to the system. (2) Users who know how to
               exploit this vulnerability may be able to read files they would
               not normally have access to.
SOLUTION:      Apply the fixes described below.
______________________________________________________________________________
VULNERABILITY  Instructions on how to exploit these vulnerabilities have been
ASSESSMENT:    published on the Internet.
______________________________________________________________________________

[ Start IBM-ERS Bulletins ]

1. Vulnerability in gethostbyname() library function

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                           EMERGENCY RESPONSE SERVICE
			  SECURITY VULNERABILITY ALERT

03 December 1996 18:30 GMT                       Number: ERS-SVA-E01-1996:007.1
===============================================================================
                             VULNERABILITY  SUMMARY

VULNERABILITY:  Possible buffer overrun condition in "gethostbyname()" library
	        function

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

SOLUTION:	Apply the fixes described below

THREAT:		If exploited, this condition may permit unauthorized super-user
		access to the system

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

I. Description

In TCP/IP networks such as the Internet and many corporate networks, hosts are
identified by 32-bit numbers called addresses.  However, because these numbers
are difficult to remember, names are also given to hosts.  Although people use
the names to refer to the hosts, computer software must translate these names
into the numeric addresses in order to use them.

The Domain Name System (DNS), also called "the name server," is the primary
database used to perform these name-to-address (and address-to-name)
translations.  Other databases, such as the Network Information System (NIS,
formerly called Yellow Pages) and the "hosts file" are also used on some
systems.

When a program on a UNIX system wants to look up a host's name and obtain its
network address, it uses a library function called "gethostbyname()."  This
function takes a host name as a parameter, contacts the Domain Name System (or
another source of information), and returns the host's address(es) to the
program.  This saves the programmer the trouble of writing the complex code to
interface with the name server.

Under certain conditions, the "gethostbyname()" library function provided with
IBM AIX versions 3.2.x, 4.1.x, and 4.2.x can encounter a buffer overrun that
allows information on the program stack to be corrupted.

II. Impact

Many set-user-id and set-group-id programs, as well as many network programs
running with super-user privileges, make use of the "gethostbyname()" library
function.  Corrupting the program stack of these programs may allow arbitrary
user-provided code to be executed inadvertently.

If successfully exploited, this buffer overrun condition could be used to gain
super-user access to the system.  Such an action could be initiated over the
network from a remote system, or by a user on the local system.  Penetration
through a firewall may also be possible, depending on which services and
applications are permitted by the firewall system.

A script that exploits a similar buffer overrun condition in the Sun Solaris
2.x version of "gethostbyname()" was publicly released in November, 1996.  Sun
Microsystems announced fixes for that condition in Security Bulletin 137, which
was released on 20 Nov 96.

As of this writing, IBM-ERS is not aware of any similar exploitation script for
the AIX operating system, nor are we aware of any successful exploitations of
this condition (against either AIX systems or Solaris systems).

III. Solutions

The following Automated Program Analysis Reports (APARs) for IBM AIX are now
available to address the concerns described above:

  AIX 3.2.x
  ---------
    APAR - IX60927 (PTF - U443452,U444191,U444206,U444213,U444233,U444244)

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

        lslpp -lB U443452 U444191 U444206 U444213 U444233 U444244

  AIX 4.1.x
  ---------
    APAR - IX61019

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

       instfix -ik IX61019

  AIX 4.2.x
  ---------
    APAR - IX62144

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

       instfix -ik IX62144

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.

IV. Acknowledgements

IBM-ERS would like to thank the CERT Coordination Center (CERT/CC), AUSCERT,
Sun Microsystems, and Marko Laakso (University of Oulu) for providing some of
the information in this advisory.

AIX is a registered trademark of International Business Machines Corporation.

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

2. Vulnerability in "lquerypv" command

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

                           EMERGENCY RESPONSE SERVICE
			  SECURITY VULNERABILITY ALERT

03 December 1996 18:30 GMT                       Number: ERS-SVA-E01-1996:008.1
===============================================================================
                             VULNERABILITY  SUMMARY

VULNERABILITY:	The "lquerypv" command does not correctly enforce file access
		permissions.

PLATFORMS:	IBM AIX(r) 4.1, 4.2

SOLUTION:	Apply the fix described below.

THREAT:		Users who know how to exploit this vulnerability may be able to
		read files they would not normally have access to.

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

I. Description

The "lquerypv" command is an undocumented, low-level worker program that is a
part of the AIX Logical Volume Manager family of commands.  When installed, the
"lquerypv" command is set-user-id "root", which allows it to run with
super-user access permissions.

When invoked with the "-h" option, "lquerypv" does not adequately enforce the
read permissions on files when it is run by regular (non-"root") users.  This
can allow users to obtain access to the contents of files that they are not
authorized to read.

Instructions for exploiting this vulnerability were made available on USENET
newsgroups and Internet mailing lists in November, 1996.

II. Impact

Allowing users to obtain unauthorized access to file contents can reveal such
confidential information as encrypted passwords, electronic mail, and other
data.

III. Solutions

  A. How to alleviate the problem

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

	 chmod u-s /usr/sbin/lquerypv

     Note that this action will cause some Logical Volume Manager commands to
     fail when they are executed by non-"root" users (such as "lsps").  It will
     not affect the operation of these commands when they are executed by
     "root".

  B. Official fix

     The following Automated Program Analysis Reports (APARs) for IBM AIX are
     now available to address this problem:

     AIX 3.2.x
     ---------
       Not vulnerable; no fix necessary.

     AIX 4.1.x
     ---------
       APAR - IX64203

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

	   instfix -ik IX64203
	
       Or, run this command:

	   lslpp -h bos.rte.lvm

       and verify that your version of bos.rte.lvm is 4.1.5.3 or later.

     AIX 4.2.x
     ---------
       APAR - IX64204

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

	   instfix -ik IX64204
	
       Or, run this command:

	   lslpp -h bos.rte.lvm

       and verify that your version of bos.rte.lvm is 4.2.0.7 or later.

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

IBM-ERS would like to thank Andrew Pechenov <andy@bor.compnet.ru> for bringing
this vulnerability to our attention.

AIX is a registered trademark of International Business Machines Corporation.

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

[ End IBM-ERS Bulletins ]

_______________________________________________________________________________

CIAC wishes to acknowledge the contributions of IBM-ERS for the
information contained in this bulletin.
_______________________________________________________________________________

CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
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LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)

H-02: SUN's TCP SYN Flooding Solutions
H-03: HP-UX_suid_Vulnerabilities
H-04: HP-UX  Ping Vulnerability
H-05: Internet Hoaxes
H-07: Sendmail SIGHUP-smtpd Vulnerability
H-08: lpr Buffer Overrun Vulnerability
H-09: HP 9000 Access Vulnerability
H-10: HP-UX Security Vulnerabilities (passwd, fpkg2swpkg, newgrp)
H-11: sendmail Group Permissions Vulnerability
H-12: IBM AIX(r) 'SYN Flood' and 'Ping o' Death' Vulnerabilities

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