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Cisco Security Advisory: Denial of Service Vulnerabilities
in Content
Switching Module
Document ID: 97826
Advisory ID: cisco-sa-20070905-csm
http://www.cisco.com/warp/public/707/cisco-sa-20
070905-csm.shtml
Revision 1.0
For Public Release 2007 September 5 1600 UTC (GMT)
-
------------------------------------------------------------
---------
Summary
=======
The Cisco Content Switching Modules (CSM) and Cisco Content
Switching
Module with SSL (CSM-S) contain two vulnerabilities that can
lead to
a denial of service (DoS) condition. The first vulnerability
exists
when processing TCP packets, and the second vulnerability
affects
devices with service termination enabled.
Cisco has made free software available to address these
vulnerabilities for affected customers.
This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20
070905-csm.shtml
Affected Products
=================
Vulnerable Products
+------------------
These vulnerabilities were identified in CSM software
version 4.2 and
CSM-S software version 2.1. The following table helps
illustrate the
vulnerable software versions for these products:
+---------------------------------------+
| Vulnerability | CSM | CSM-S |
|---------------+-----------+-----------|
| TCP packet | 4.2 Prior | 2.1 Prior |
| Processing | to 4.2.3a | to 2.1.2a |
| DOS | | |
|---------------+-----------+-----------|
| Service | 4.2 Prior | 2.1 Prior |
| Termination | to 4.2.7 | to 2.1.6 |
+---------------------------------------+
To determine the software running on a Content Switching
Module, log
in to the Catalyst switch and issue the show version
command.
The following example shows a CSM running software version
4.2(2) in
a Supervisor running CatOS. Supervisors running CatOS or IOS
will
have similar output. The version of the CSM is shown on the
module
labeled WS-X6066-SLB-APC as illustrated in the following
output.
Console>show version
WS-C6506 Software, Version NmpSW: 7.6(9)
Copyright (c) 1995-2004 by Cisco Systems
NMP S/W compiled on Aug 27 2004, 20:05:14
System Bootstrap Version: 7.1(1)
System Boot Image File is
'disk0:cat6000-sup2k8.7-6-9.bin'
System Configuration register is 0x2102
Hardware Version: 3.0 Model: WS-C6506 Serial #:
TBA05360375
PS1 Module: WS-CAC-1300W Serial #: ACP05061071
PS2 Module: WS-CAC-1300W Serial #: ACP05060407
Mod Port Model Serial # Versions
--- ---- ------------------- -----------
--------------------------------------
1 2 WS-X6K-SUP2-2GE SAD055104YY Hw : 3.2
Fw : 7.1(1)
Fw1: 6.1(3)
Sw : 7.6(9)
Sw1: 7.6(9)
WS-F6K-PFC2 SAD055104H5 Hw : 3.0
Sw :
WS-X6K-SUP2-2GE SAD055104YY Hw : 3.2
Sw :
2 48 WS-X6248-RJ-45 SAD0501084U Hw : 1.4
Fw : 5.4(2)
Sw : 7.6(9)
5 4 WS-X6066-SLB-APC SAD105003DW Hw : 1.9
Fw :
Sw : 4.2(2)
DRAM FLASH
NVRAM
Module Total Used Free Total Used Free
Total Used Free
------ ------- ------- ------- ------- ------- -------
----- ----- -----
1 262144K 70354K 191790K 32768K 23251K 9517K
512K 253K 259K
Uptime is 43 days, 22 hours, 7 minutes
The following configuration segment shows a vserver with
service
terminations enabled:
vserver WWW:2
virtual x.x.x.x tcp www service termination
Products Confirmed Not Vulnerable
+--------------------------------
Only Catalyst CSM modules running indicated 4.2 versions are
affected
by these vulnerabilities. CSM software versions 4.1, 3.2 and
3.1 are
not affected by these vulnerabilities.
Catalyst CSM-S modules running indicated 2.1 versions are
the only
vulnerable versions of software for that product.
No other Cisco products are currently known to be affected
by this
vulnerability. The Cisco Secure Content Accelerator is not
affected
by this vulnerability.
Details
=======
The Catalyst CSM is an integrated Server Load Balancing line
card for
the Catalyst 6500 and 7600 Series designed to enhance the
response
time for client traffic to end points including servers,
caches,
firewalls, Secure Sockets Layer (SSL) devices, and VPN
termination
devices.
The Catalyst 6500 CSM-S combines high-performance server
load
balancing (SLB) with Secure Socket Layer (SSL) offload. The
CSM-S is
similar to the CSM; however, it can also terminate and
initiate
SSL-encrypted traffic, which allows the CSM-S to perform
intelligent
load balancing while ensuring secure end-to-end encryption.
When a module running affected code receives specific TCP
packets out
of order, a DoS condition may be triggered resulting in the
CPU
reaching 100% utilization or a reload with a FPGA4 exception
with
icp.fatPath length error.
This vulnerability is documented in Cisco bug ID
CSCsd27478.
When service termination is enabled on a module running
affected
software and the module is under high network utilization, a
DoS
condition may be triggered, resulting in a reload with a
FPGA4
exception 1 IDLE error.
This vulnerability is documented in Cisco bug ID
CSCsh57876.
In normal operations, the MSFC CLI handles the management of
the CSM
and CSM-S; however, in order to upgrade the software, a user
must
first log into the switch and session to the module.
For more information on how to upgrade your CSM, visit the
http://www.cisco.c
om/en/US/products/hw/modules/ps2706/products_tech_note09186a
0080094526.shtml
page on Cisco.com.
Information on how to upgrade the CSM-S can be found at:
http://www.cisco.com/en/US/docs/interfaces_module
s/services_modules/csms/2.1.1/configuration/guide/getstart.h
tml#wp1041858.
Vulnerability Scoring Details
=============================
Cisco is providing scores for the vulnerabilities in this
advisory
based on the Common Vulnerability Scoring System (CVSS). The
CVSS
scoring in this Security Advisory is done in accordance with
CVSS
version 2.0.
Cisco will provide a base and temporal score. Customers can
then
compute environmental scores to assist in determining the
impact of
the vulnerability in individual networks.
Customers are encouraged to apply the bias parameter when
determining
the environmental impact of a particular vulnerability.
CVSS is a standards based scoring method that conveys
vulnerability
severity and helps determine urgency and priority of
response.
Cisco has provided an FAQ to answer additional questions
regarding
CVSS at
http://www.cisco.com/web/about/security/int
elligence/cvss-qandas.html
Cisco has also provided a CVSS calculator to help compute
the
environmental impact for individual networks at
http://intellishield.cisco.com/security/alertmanager/cv
ss
CSCsh57876 - FPGA4 exception under high network utilization
and
service termination is enabled
CVSS Base Score: 7.8
Access Vector: Network
Access Complexity: Low
Authentication: None
Confidentiality Impact: None
Integrity Impact: None
Availability Impact: Complete
Impact Bias: Normal
CVSS Temporal Score: 6.4
Exploitability: Functional
Remediation Level: Official Fix
Report Confidence: Confirmed
CSCsh57876 - FPGA4 exception with icp.fatPath length error
when out of order
packets are received
CVSS Base Score: 7.8
Access Vector: Network
Access Complexity: Low
Authentication: None
Confidentiality Impact: None
Integrity Impact: None
Availability Impact: Complete
Impact Bias: Normal
CVSS Temporal Score: 6.4
Exploitability: Functional
Remediation Level: Official Fix
Report Confidence: Confirmed
Impact
======
Successful exploitation of these vulnerabilities against a
system
running a vulnerable version of CSM or CSM-S software may
cause the
system to become unresponsive or reload. Repeated attacks
may result
in a prolonged DoS condition.
Software Versions and Fixes
===========================
When considering software upgrades, also consult
http://www.cisco.com/go
/psirt and any subsequent advisories to
determine exposure and a complete upgrade solution.
In all cases, customers should exercise caution to be
certain the
devices to be upgraded contain sufficient memory and that
current
hardware and software configurations will continue to be
supported
properly by the new release. If the information is not
clear, contact
the Cisco Technical Assistance Center ("TAC") or
your contracted
maintenance provider for assistance.
For more information on the terms "Rebuild" and
"Maintenance," consult
the following URL:
http://www.cisc
o.com/en/US/products/sw/iosswrel/ps1828/products_white_paper
09186a008018305e.shtml
Registered customers can obtained fixed software for the CSM
from:
http://www.cisco.com/pcgi-bin/tablebuild.pl/
cat6000-csm?psrtdcat20e2
Registered customers can obtained fixed software for the
CSM-S from:
http://www.cisco.com/pcgi-bin/tablebuild.pl
/cat6000-csms?psrtdcat20e2
Workarounds
===========
There are no workarounds for these vulnerabilities. Removing
service
termination will mitigate Cisco bug ID CSCsh57876; however,
disabling
this feature disables services that may be critical to the
operation
of the device.
Additional mitigations that can be deployed on Cisco devices
within
the network are available in the Cisco Applied Intelligence
companion
document for this advisory:
http://www.cisco.com/warp/public/707/cisco-air-
20070905-csm.shtml
Obtaining Fixed Software
========================
Cisco will make free software available to address this
vulnerability
for affected customers. This advisory will be updated as
fixed
software becomes available. Prior to deploying software,
customers
should consult their maintenance provider or check the
software for
feature set compatibility and known issues specific to
their
environment.
Customers may only install and expect support for the
feature sets
they have purchased. By installing, downloading, accessing
or
otherwise using such software upgrades, customers agree to
be bound by
the terms of Cisco's software license terms found at
http://www.cisco.com/public/sw-license-agreement.html,
or as otherwise
set forth at Cisco.com Downloads at
http://www.cisco.com/public/sw-center/sw-usingswc.shtml.
Do not contact either "psirt cisco.com" or
"security-alertcisco.com"
for software upgrades.
Customers with Service Contracts
+-------------------------------
Customers with contracts should obtain upgraded software
through
their regular update channels. For most customers, this
means that
upgrades should be obtained through the Software Center on
Cisco's
worldwide website at http://www.cisco.com.
Customers using Third Party Support Organizations
+------------------------------------------------
Customers whose Cisco products are provided or maintained
through
prior or existing agreement with third-party support
organizations
such as Cisco Partners, authorized resellers, or service
providers
should contact that support organization for guidance and
assistance
with the appropriate course of action in regards to this
advisory.
The effectiveness of any workaround or fix is dependent on
specific
customer situations such as product mix, network topology,
traffic
behavior, and organizational mission. Due to the variety of
affected
products and releases, customers should consult with their
service
provider or support organization to ensure any applied
workaround or
fix is the most appropriate for use in the intended network
before it
is deployed.
Customers without Service Contracts
+----------------------------------
Customers who purchase direct from Cisco but who do not hold
a Cisco
service contract and customers who purchase through
third-party
vendors but are unsuccessful at obtaining fixed software
through
their point of sale should get their upgrades by contacting
the Cisco
Technical Assistance Center (TAC). TAC contacts are as
follows.
* +1 800 553 2447 (toll free from within North America)
* +1 408 526 7209 (toll call from anywhere in the world)
* e-mail: taccisco.com
Have your product serial number available and give the URL
of this
notice as evidence of your entitlement to a free upgrade.
Free
upgrades for non-contract customers must be requested
through the
TAC.
Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC
.shtml
for additional TAC contact information, including special
localized
telephone numbers and instructions and e-mail addresses for
use in
various languages.
Exploitation and Public Announcements
=====================================
The Cisco PSIRT is not aware of any public announcements or
malicious
use of the vulnerability described in this advisory.
These vulnerabilities were discovered during the
investigation of
customer support cases.
Status of this Notice: Final
============================
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND
DOES NOT IMPLY ANY
KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF
THE
INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE
DOCUMENT IS
AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR
UPDATE THIS
DOCUMENT AT ANY TIME.
A stand-alone copy or Paraphrase of the text of this
document that
omits the distribution URL in the following section is an
uncontrolled copy, and may lack important information or
contain
factual errors.
Distribution
============
This advisory is posted on Cisco's worldwide website at:
http://www.cisco.com/warp/public/707/cisco-sa-20
070905-csm.shtml
In addition to worldwide web posting, a text version of this
notice
is clear-signed with the Cisco PSIRT PGP key and is posted
to the
following e-mail and Usenet news recipients.
* cust-security-announcecisco.com
* first-teamsfirst.org
* bugtraqsecurityfocus.com
* vulnwatchvulnwatch.org
* ciscospot.colorado.edu
* cisco-nsppuck.nether.net
* full-disclosurelists.grok.org.uk
* comp.dcom.sys.cisconewsgate.cisco.com
Future updates of this advisory, if any, will be placed on
Cisco's
worldwide website, but may or may not be actively announced
on
mailing lists or newsgroups. Users concerned about this
problem are
encouraged to check the above URL for any updates.
Revision History
================
+---------------------------------------+
| Revision | | Initial |
| 1.0 | 2007-Sept-05 | public |
| | | release |
+---------------------------------------+
Cisco Security Procedures
=========================
Complete information on reporting security vulnerabilities
in Cisco
products, obtaining assistance with security incidents, and
registering to receive security information from Cisco, is
available
on Cisco's worldwide website at
http://www.cisco.com/en/US/produc
ts/products_security_vulnerability_policy.html
This includes instructions for press inquiries regarding
Cisco
security notices. All Cisco security advisories are
available at
http://www.cisco.com/g
o/psirt.
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