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AUSCERT External Security Bulletin Redistribution
ESB-2006.0700 -- [AIX]
Vulnerability in rdist may allow for arbitrary file overwrite
27 September 2006
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: rdist
Publisher: IBM
Operating System: AIX 5.3
AIX 5.2
Impact: Overwrite Arbitrary Files
Access: Existing Account
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IBM SECURITY ADVISORY
First Issued: Mon Sep 25 10:00 CDT 2006
==========================================================================
VULNERABILITY SUMMARY
VULNERABILITY: A vulnerability in the rdist command may allow a user
to overwrite an arbitrary file.
PLATFORMS: AIX 5.2 and 5.3.
SOLUTION: Apply the APAR, interim fix or workaround as
described below.
THREAT: A local user may overwrite an arbitrary file
resulting in a denial of service.
CERT VU Number: n/a
CVE Number: n/a
==========================================================================
DETAILED INFORMATION
I. Description
===============
A vulnerability has been discovered in the rdist command that may allow a
local user to overwrite an arbitrary file. The rdist command maintains
identical copies of files on multiple hosts. This vulnerability pertains to
/usr/bin/rdist. It does not pertain to /usr/sbin/rdist.
rdist ships as part of the bos.net.tcp.client fileset. Executing the
following command will list the fileset along with its version information,
state, type and a description if it is installed:
# lslpp -L bos.net.tcp.client
The following table shows the vulnerable versions of bos.net.tcp.client.
AIX Release Lower Upper
Level Level
===========================================
AIX 5.2 5.2.0.0 5.2.0.95
AIX 5.3 5.3.0.0 5.3.0.51
II. Impact
==========
A local user may execute arbitrary code as the root user.
III. Solutions
===============
A. APARs
IBM provides the following fixes:
APAR number for AIX 5.2.0: IY88688 (available)
APAR number for AIX 5.3.0: IY88687 (available approx. 10/04/06)
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/rdist_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 interim fixes below are named by using the APAR corresponding to the
release that the fix applies to. The APAR is followed by an underscore and
the Technology Level for the particular AIX release that a fix applies to.
The checksums below were generated using the "sum" and "md5sum" commands
and are as follows:
Filename sum md5
=========================================================================
IY88688_07.060828.epkg.Z 64303 78 218750f34da5de39fd31ffcf6f72708b
IY88688_08.060920.epkg.Z 18481 78 d4c0551ae0f6a5ea73f8cba02995eb69
IY88688_09.060828.epkg.Z 48230 80 e37e8b0914db32c71f47064a36ab638a
IY88687_03.060828.epkg.Z 21740 79 0f433db52a3ea04311d2fd72b30f11f6
IY88687_04.060828.epkg.Z 12022 79 8559a845f365715b3b3b957ab603016f
IY88687_05.060908.epkg.Z 33493 79 a10ac1b45eb6efdf60c16a89d985e2b4
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 interim fixes include prerequisite checking. This will ensure the
correct mapping between the interim fixes and AIX Technology Levels. The
following table shows the prerequisite fileset levels required for the
fixes above. The fileset levels listed are for bos.net.tcp.client
Interim Fileset Level Fileset Level
Fix (lower limit) (upper limit)
===================================================================
IY88688_07.060828.epkg.Z 5.2.0.75 5.2.0.78
IY88688_08.060920.epkg.Z 5.2.0.85 5.2.0.88
IY88688_09.060828.epkg.Z 5.2.0.95 5.2.0.95
IY88687_03.060828.epkg.Z 5.3.0.30 5.3.0.32
IY88687_04.060828.epkg.Z 5.3.0.40 5.3.0.44
IY88687_05.060908.epkg.Z 5.3.0.50 5.3.0.51
IMPORTANT: If possible, it is recommended that a mksysb backup of the
system is created. Verify it is both bootable, and readable before
proceeding.
Customers may contact IBM support if any issues arise with these interim
fixes.
Interim Installation Instructions:
+---------------------------------
These packages use the new Interim Fix Management Solution to install and
manage interim fixes. More information can be found at:
http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html
To preview an epkg interim fix installation execute the following command:
# emgr -e ipkg_name -p # where ipkg_name is the name of the
# interim fix package being previewed.
To install an epkg interim fix package, execute the following command:
# emgr -e ipkg_name -X # where ipkg_name is the name of the
# interim fix package being installed.
The "X" flag will expand any filesystems if required.
C. Workaround
Remove the setuid root bit. Note that this will prevent rdist from
functioning normally for non-root users. This can be done by executing the
following command:
# chmod 555 /usr/bin/rdist
Verify the changes:
# ls -la /usr/bin/rdist
- - -r-xr-xr-x 1 root bin 58542 May 13 2004 /usr/bin/rdist
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 0x1B14F299.
Please contact your local IBM AIX support center for any assistance.
eServer is a trademark of International Business Machines Corporation.
IBM, AIX and pSeries are registered trademarks of International Business
Machines Corporation. All other trademarks are property of their respective
holders.
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