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AUSCERT External Security Bulletin Redistribution
ESB-2012.0131
AIX: TCP Denial of service
6 February 2012
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: AIX
Publisher: IBM
Operating System: AIX
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2012-0194
Original Bulletin:
http://www14.software.ibm.com/webapp/set2/subscriptions/pqvcmjd?mode=18&ID=5706&myns=paix53&mync=E
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IBM SECURITY ADVISORY
First Issued: Fri Feb 3 10:20:44 CST 2012
The most recent version of this document is available here:
http://aix.software.ibm.com/aix/efixes/security/large_send_advisory.asc
===============================================================================
VULNERABILITY SUMMARY
VULNERABILITY: Vulnerability in AIX TCP stack
PLATFORMS: AIX 5.3, 6.1, and 7.1 releases
SOLUTION: Apply the fix as described below.
THREAT: TCP network packet denial of service
CVE Number: CVE-2012-0194
Reboot required? YES
Workarounds? YES
Protected by FPM? NO
Protected by SED? NO
===============================================================================
DETAILED INFORMATION
I. DESCRIPTION
AIX could allow a remote attacker to cause a denial of service, caused by
an error when the TCP large send offload option is enabled on a network
interface. By sending a specially-crafted sequence of packets, an attacker
could exploit this vulnerability to cause a kernel panic.
II. CVSS
CVSS Base Score: 7.1 CVSS Temporal Score: See
http://xforce.iss.net/xforce/xfdb/72562 for the current score CVSS
Environmental Score*: Undefined CVSS String: (AV:n/AC:m/Au:n/C:n/I:n/A:c)
III. 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 5.3.12.0 5.3.12.5
bos.net.tcp.client 6.1.5.0 6.1.5.8
bos.net.tcp.client 6.1.6.0 6.1.6.17
bos.net.tcp.client 6.1.7.0 6.1.7.3
bos.net.tcp.client 7.1.0.0 7.1.0.17
bos.net.tcp.client 7.1.1.0 7.1.1.3
IV. SOLUTIONS
A. APARS
IBM has assigned the following APARs to this problem:
AIX Level APAR number Availability
---------------------------------------------------
5.3.12 IV13827 TBD sp6
6.1.5 IV13751 TBD sp9
6.1.6 IV13820 TBD sp8
6.1.7 IV14209 TBD sp4
7.1.0 IV14210 TBD sp5
7.1.1 IV14211 TBD sp4
Subscribe to the APARs here:
http://www.ibm.com/support/docview.wss?uid=isg1IV13827
http://www.ibm.com/support/docview.wss?uid=isg1IV13751
http://www.ibm.com/support/docview.wss?uid=isg1IV13820
http://www.ibm.com/support/docview.wss?uid=isg1IV14209
http://www.ibm.com/support/docview.wss?uid=isg1IV14210
http://www.ibm.com/support/docview.wss?uid=isg1IV14211
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 available. The fixes can be downloaded via ftp
from:
ftp://aix.software.ibm.com/aix/efixes/security/large_send_fix.tar
The link above is 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 Interim Fix (*.Z)
-------------------------------------------------------------------
5.3.12.5 53XSP5_IV13827s05.120126.epkg.Z
6.1.5.7 61JSP7_IV13751s07.120126.epkg.Z
6.1.6.16 61NSP6_IV13820s06.120126.epkg.Z
6.1.7.2 61QS02_IV14209s02.120126.epkg.Z
7.1.0.17 71BSP4_IV14210s04.120129.epkg.Z
7.1.1.02 71DSP2_IV14211s02.120126.epkg.Z
To extract the fixes from the tar file:
tar xvf large_send_fix.tar
cd large_send_fix
Verify you have retrieved the fixes intact:
The checksums below were generated using the
"csum -h SHA1" (sha1sum) command is the followng:
csum -h SHA1 (sha1sum) filename
- ------------------------------------------------------------------
788096451a8e621a04bf8967b9c55cbe18fe334a 53XSP5_IV13827s05.120126.epkg.Z
37aca7ad354a8e0775152f6801c0d9790a990782 61JSP7_IV13751s07.120126.epkg.Z
637048a0ab3764d712a837815cccf355bf4be245 61NSP6_IV13820s06.120126.epkg.Z
12fddcb7e3ee87144a8ed8008c4e40ea70df8262 61QS02_IV14209s02.120126.epkg.Z
246e09b69f741a1c552042c065bfc0854167c5f3 71BSP4_IV14210s04.120129.epkg.Z
5945422d284849fd2f268a5b54a62eeb2fcae18b 71DSP2_IV14211s02.120126.epkg.Z
To verify the sum, use the text of this advisory as input to sha1sum.
For example:
csum -h SHA1 -i 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 at
security-alert@austin.ibm.com and describe the discrepancy.
C. FIX AND 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.
To preview a fix installation:
installp -a -d fix_name -p all # where fix_name is the name of the
#fix package being previewed.
To install a fix package:
installp -a -d fix_name -X all # where fix_name is the name of the
#fix package being installed.
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.
V. WORKAROUNDS
Adjust the lowest value from the common path MTUs table based on customer
configuration. Turn off large send function (may have performance impact) Turn
off path MTU discovery (may have performance impact)
VI. OBTAINING FIXES
AIX security fixes can be downloaded from:
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.
VII. 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 you can either:
A. Send an email with "get key" in the subject line to:
security-alert@austin.ibm.com
B. Download the key from a PGP Public Key Server. The key ID is:
0x28BFAA12
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.
VIII. REFERENCES:
Complete CVSS Guide: http://www.first.org/cvss/cvss-guide.html On-line
Calculator V2: http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2 X-Force
Vulnerability Database: http://xforce.iss.net/xforce/xfdb/72562 CVE-2012-0194:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-0194
*The CVSS Environment Score is customer environment specific and will
ultimately impact the Overall CVSS Score. Customers can evaluate the impact of
this vulnerability in their environments by accessing the links in the
Reference section of this Flash.
Note: According to the Forum of Incident Response and Security Teams
(FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open
standard designed to convey vulnerability severity and help to determine
urgency and priority of response." IBM PROVIDES THE CVSS SCORES "AS IS"
WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE
RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY
VULNERABILITY.
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