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ESB-2007.0370 -- [AIX] -- A vulnerability in the Perl interpreter may allow a local user to execute arbitrary code as another user

Date: 12 July 2007

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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                          ESB-2007.0370 -- [AIX]
         A vulnerability in the Perl interpreter may allow a local
              user to execute arbitrary code as another user
                               12 July 2007

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

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              Perl
Publisher:            IBM
Operating System:     AIX 5.2, 5.3
Impact:               Increased Privileges
Access:               Existing Account

Revision History:     July 12 2007: New interim fixes are now available
                      May 31 2007: Initial Release

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IBM SECURITY ADVISORY


First Issued: Tue May 22 14:00:24 CDT 2007
| Updated: Tue Jun 12 08:09:47 CDT 2007

===========================================================================
                           VULNERABILITY SUMMARY

VULNERABILITY:      A vulnerability in the Perl interpreter may allow a
                    local user to execute arbitrary code as another
                    user.

PLATFORMS:          AIX 5.2 and AIX 5.3.

SOLUTION:           Install the interim fixes or APARs as described below.

THREAT:             A local user may execute arbitrary code as another
                    user.

CERT VU Number:     n/a
CVE Number:         n/a
===========================================================================
                           DETAILED INFORMATION


I.  Description
===============

A vulnerability exists in the AIX Perl interpreter and other related Perl
binaries that allows a local user to execute arbitrary code as another
user. To successfully exploit this vulnerability, an attacker must wait for
a legitimate user to execute a binary that ships with Perl. The arbitrary
code will run with the privileges of the legitimate user.

The following table shows which filesets are affected by this issue:

AIX Release          Fileset           Lower         Upper
                                       Level         Level
=============================================================
| AIX 5.2              perl.rte          5.8.0.10      5.8.0.105
| AIX 5.3              perl.rte          5.8.2.10      5.8.2.60

| Update: AIX 5200-10 and AIX 5300-06 are also affected.

Perl binaries ship as part of the perl.rte fileset. To determine which
version of a given fileset is installed, execute the following command:

| # lslpp -L | grep perl.rte

The fileset will be listed along with its version information, state, type
and a description.


II. Impact
==========

A local user may execute arbitrary code as another user.


III.  Solutions
===============

A. Official Fix

IBM provides the following fixes:

      APAR number for AIX 5.2.0:  IY98394 (available approx. 07/25/07)
      APAR number for AIX 5.3.0:  IY98395 (available approx. 07/04/07)

NOTE: Affected customers are urged to upgrade to the latest applicable
Technology Level.

B. Interim Fix

Interim fixes are available. The interim fixes can be downloaded via ftp
from:

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

This is a compressed tarball containing this advisory, interim fix packages
and cleartext PGP signatures for each package.


Verify you have retrieved the fixes intact:
+------------------------------------------
The checksums below were generated using the "sum" and "md5sum" commands
and are as follows:

Filename                sum           md5
======================================================================
IY98394.051407.epkg.Z   63922 14844   6fe2f7bd7f4cc66c5acba17a71361baf
IY98395.051407.epkg.Z   20736 15234   d7977aea2a5c364634fe3f2dbd805899
| IY98394.060607.epkg.Z   60616 14831   5a26e2bd03b090976505c203759bb39b
| IY98395.060607.epkg.Z   10126 15223   542fd649aa7cac74d37ba2b4b06ecc2f

| UPDATE: New interim fixes are now available to support affected releases:

|     AIX 5200-10: IY98394.060607.epkg.Z
|     AIX 5300-06: IY98395.060607.epkg.Z

These sums should match exactly. The PGP signatures in the compressed
tarball and on this advisory can also be used to verify the integrity of
the various files they correspond to. If the sums or signatures cannot be
confirmed, double check the command results and the download site address.
If those are OK, contact IBM AIX Security at security-alert@austin.ibm.com
and describe the discrepancy.

The following table shows the prerequisite fileset level for the fixes
above. These levels are for perl.rte.


Interim                    Fileset Level     Fileset Level   AIX
Fix                        (lower level)     (upper level)   Release
====================================================================
IY98394.051407.epkg.Z      5.8.0.10          5.8.0.95        AIX 5.2
IY98395.051407.epkg.Z      5.8.2.10          5.8.2.50        AIX 5.3
| IY98394.060607.epkg.Z      5.8.0.96          5.8.0.105       AIX 5.2
| IY98395.060607.epkg.Z      5.8.2.51          5.8.2.60        AIX 5.3

IMPORTANT: If possible, it is recommended that a mksysb backup of the
system is created. Verify it is both bootable, and readable before
proceeding.


Interim Installation Instructions:
+---------------------------------

These packages use the new Interim Fix Management Solution to install and
manage ifixes. More information can be found at:

     http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html

To preview an epkg ifix installation execute the following command:

# emgr -e ipkg_name -p       # where ipkg_name is the name of the
                             # ifix package being previewed.

To install an epkg ifix package, execute the following command:

# emgr -e ipkg_name -X       # where ipkg_name is the name of the
                             # ifix package being installed.

The "X" flag will expand any filesystems if required.

IV. Obtaining Fixes
===================

AIX Version 5 APARs can be downloaded from:

     http://www.ibm.com/servers/eserver/support/unixservers/aixfixes.html

Security related Interim Fixes can be downloaded from:

     ftp://aix.software.ibm.com/aix/efixes/security


V.  Contact Information
=======================

If you would like to receive AIX Security Advisories via email, please
visit:

     http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd

Comments regarding the content of this announcement can be directed to:

     security-alert@austin.ibm.com

To request the PGP public key that can be used to communicate securely
with the AIX Security Team send email to security-alert@austin.ibm.com
with a subject of "get key". The key can also be downloaded from a PGP
| Public Key Server. The key id is 0x4265D862.

Please contact your local IBM AIX support center for any assistance.

eServer is a trademark of International Business Machines Corporation.
IBM, AIX and pSystem are registered trademarks of International Business
Machines Corporation. All other trademarks are property of their respective
holders.
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===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
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                On call after hours for member emergencies only.
===========================================================================

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