18 february, 2009
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IBM SECURITY ADVISORY
First Issued: Thu Jan 29 11:04:38 CST 2009
The most recent version of this document is available here:
http://aix.software.ibm.com/aix/efixes/security/rmsock_advisory.asc
or
ftp://aix.software.ibm.com/aix/efixes/security/rmsock_advisory.asc
===============================================================================
VULNERABILITY SUMMARY
VULNERABILITY: AIX rmsock log append file vulnerability
PLATFORMS: AIX 5.2, 5.3, 6.1
SOLUTION: Apply the fix or workaround as described below.
THREAT: A local attacker may append data to any file on the
system.
CERT VU Number: n/a
CVE Number: n/a
Reboot required? NO
Workarounds? YES
Protected by FPM? YES (high, medium, or low)
Protected by SED? NO
===============================================================================
DETAILED INFORMATION
I. OVERVIEW
The rmsock and rmsock64 commands do not create secure log files.
A local attacker may exploit this error to append data to any file
on the system because the command is setuid root.
The following files are vulnerable:
/usr/sbin/rmsock
/usr/sbin/rmsock64
II. PLATFORM VULNERABILITY ASSESSMENT
To determine if your system is vulnerable, execute the following
command:
lslpp -L bos.net.tcp.client
The following fileset levels are vulnerable:
AIX Fileset Lower Level Upper Level
---------------------------------------------------
bos.net.tcp.client 5.2.0.0 5.2.0.112
bos.net.tcp.client 5.3.0.0 5.3.0.72
bos.net.tcp.client 5.3.7.0 5.3.7.7
bos.net.tcp.client 5.3.8.0 5.3.8.6
bos.net.tcp.client 5.3.9.0 5.3.9.2
bos.net.tcp.client 6.1.0.0 6.1.0.7
bos.net.tcp.client 6.1.1.0 6.1.1.3
bos.net.tcp.client 6.1.2.0 6.1.2.2
III. SOLUTIONS
A. APARS
IBM has assigned the following APARs to this problem:
AIX Level APAR number Availability
----------------------------------------------------
5.2.0 IZ40386 Now
5.3.0 IZ42785 4/29/2009
5.3.7 IZ42786 4/29/2009
5.3.8 IZ42787 4/29/2009
5.3.9 IZ42788 4/29/2009
6.1.0 IZ41599 2/25/2009
6.1.1 IZ41593 2/25/2009
6.1.2 IZ41510 2/25/2009
Subscribe to the APARs here:
http://www.ibm.com/support/docview.wss?uid=isg1IZ40386
http://www.ibm.com/support/docview.wss?uid=isg1IZ42785
http://www.ibm.com/support/docview.wss?uid=isg1IZ42786
http://www.ibm.com/support/docview.wss?uid=isg1IZ42787
http://www.ibm.com/support/docview.wss?uid=isg1IZ42788
http://www.ibm.com/support/docview.wss?uid=isg1IZ41599
http://www.ibm.com/support/docview.wss?uid=isg1IZ41593
http://www.ibm.com/support/docview.wss?uid=isg1IZ41510
By subscribing, you will receive periodic email alerting you
to the status of the APAR, and a link to download the fix once
it becomes available.
B. FIXES
Fixes are now available. The fixes can be downloaded from:
http://aix.software.ibm.com/aix/efixes/security/rmsock_fix.tar
ftp://aix.software.ibm.com/aix/efixes/security/rmsock_fix.tar
The links above are to a tar file containing this signed
advisory, fix packages, and PGP signatures for each package.
The fixes below include prerequisite checking. This will
enforce the correct mapping between the fixes and AIX
Technology Levels.
AIX Level Fix
----------------------------------------------------
All rmsock.090129.epkg.Z
To extract the fixes from the tar file:
tar xvf rmsock_fix.tar
cd rmsock_fix
Verify you have retrieved the fixes intact:
The checksums below were generated using the "sum", "cksum",
"csum -h MD5" (md5sum), and "csum -h SHA1" (sha1sum) commands
and are as follows:
sum filename
------------------------------------
25726 2 rmsock.090129.epkg.Z
cksum filename
-------------------------------------------
3705381579 2048 rmsock.090129.epkg.Z
csum -h MD5 (md5sum) filename
----------------------------------------------------------
e805476887aa51022f8e8baf51a33988 rmsock.090129.epkg.Z
csum -h SHA1 (sha1sum) filename
------------------------------------------------------------------
ea6944eea6e9d7b2d1a4d198f5759e365e5ed88c rmsock.090129.epkg.Z
To verify the sums, use the text of this advisory as input to
csum, md5sum, or sha1sum. For example:
csum -h SHA1 -i Advisory.asc
md5sum -c Advisory.asc
sha1sum -c Advisory.asc
These sums should match exactly. The PGP signatures in the tar
file and on this advisory can also be used to verify the
integrity of the fixes. If the sums or signatures cannot be
confirmed, contact IBM AIX Security and describe the
discrepancy at the following address:
security-alert@austin.ibm.com
C. INTERIM FIX INSTALLATION
IMPORTANT: If possible, it is recommended that a mksysb backup
of the system be created. Verify it is both bootable and
readable before proceeding.
Interim fixes have had limited functional and regression
testing but not the full regression testing that takes place
for Service Packs; thus, IBM does not warrant the fully
correct functionality of an interim fix.
Interim fix management documentation can be found at:
http://www14.software.ibm.com/webapp/set2/sas/f/aix.efixmgmt/home.html
To preview an interim fix installation:
emgr -e ipkg_name -p # where ipkg_name is the name of the
# interim fix package being previewed.
To install an interim fix package:
emgr -e ipkg_name -X # where ipkg_name is the name of the
# interim fix package being installed.
IV. WORKAROUNDS
There are two workarounds available.
A. OPTION 1
Change the permissions of these commands to remove the setuid
bit using the following commands:
chmod 500 /usr/sbin/rmsock
chmod 500 /usr/sbin/rmsock64
NOTE: chmod will disable functionality of these commands for
all users except root.
B. OPTION 2 (AIX 5.3 and 6.1)
Use the File Permissions Manager (fpm) command to manage
setuid and setgid programs.
fpm documentation can be found in the AIX 6 Security Redbook
at:
http://www.redbooks.ibm.com/abstracts/sg247430.html
An fpm level of high, medium, or low will remove the setuid
bit from the affected commands. For example:
fpm -l high -p # to preview changes
fpm -l high # to execute changes
NOTE: Please review the documentation before execution. fpm
will disable functionality of multiple commands for all users
except root.
V. OBTAINING FIXES
AIX security fixes can be downloaded from:
http://aix.software.ibm.com/aix/efixes/security
or
ftp://aix.software.ibm.com/aix/efixes/security
AIX fixes can be downloaded from:
http://www.ibm.com/eserver/support/fixes/fixcentral/main/pseries/aix
NOTE: Affected customers are urged to upgrade to the latest
applicable Technology Level and Service Pack.
VI. CONTACT INFORMATION
If you would like to receive AIX Security Advisories via email,
please visit:
http://www.ibm.com/systems/support
and click on the "My notifications" link.
To view previously issued advisories, 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 obtain the PGP public key that can be used to communicate
securely with the AIX Security Team you can either:
A. Download the key from our web page:
http://www.ibm.com/systems/resources/systems_p_os_aix_security_pgpkey.txt
B. Download the key from a PGP Public Key Server. The key ID is:
0xADA6EB4D
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.
VII. ACKNOWLEDGMENTS
IBM discovered and fixed this vulnerability as part of its
commitment to secure the AIX operating system.
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