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Cisco Security Advisory: Cisco Catalyst 6000, 6500 and Cisco
7600
Series MPLS Packet Vulnerability
Advisory ID: cisco-sa-20070228-mpls
Revision 1.0
For Public Release 2007 February 28
-
------------------------------------------------------------
---------
Summary
=======
Cisco Catalyst 6500 series systems that are running certain
versions
of Cisco Internetwork Operating System (IOS) are vulnerable
to an
attack from a Multi Protocol Label Switching (MPLS) packet.
Only the
systems that are running in Hybrid Mode (Catalyst OS (CatOS)
software
on the Supervisor Engine and IOS Software on the Multilayer
Switch
Feature Card (MSFC)) or running with Cisco IOS Software
Modularity
are affected.
MPLS packets can only be sent from the local network
segment.
This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-2
0070228-mpls.shtml
Affected Products
=================
Vulnerable Products
+------------------
The following products are affected by this vulnerability:
* Cisco Catalyst 6500 systems that run 12.2(18)SXF4 with
Cisco IOS
Software Modularity are affected.
Images that support Cisco IOS Software Modularity have a
"-vz"
suffix in their image name.
The following is a conclusive list of all image names
that are
running with Cisco IOS Software Modularity and are
affected by
this vulnerability.
+ s72033-adventerprisek9_wan-vz.122-18.SXF4.bin
+ s72033-advipservicesk9_wan-vz.122-18.SXF4.bin
+ s72033-entservicesk9_wan-vz.122-18.SXF4.bin
+ s72033-ipservices_wan-vz.122-18.SXF4.bin
+ s72033-ipservicesk9_wan-vz.122-18.SXF4.bin
+ s72033-ipservicesk9-vz.122-18.SXF4.bin
* Cisco Catalyst 6000, 6500 and Cisco 7600 series systems
with an
MSFC2 or MSFC3 that run in Hybrid Mode are affected.
In Hybrid Mode, Catalyst OS (CatOS) software runs on
the
Supervisor Engine and IOS runs on the MSFC. It is
different from
the Native Mode in which IOS runs both on the Supervisor
Engine
and MSFC.
This vulnerability affects MSFC2, MSFC2a and MSFC3 that
run
certain images in Hybrid mode.
In Hybrid Mode, IOS images that run on MSFC start with
"c6msfc2",
"c6msfc2a" or "c6msfc3". Several
image names that run on MSFC in
hybrid mode are provided below for reference:
+ c6msfc2a-adventerprisek9_wan-mz.122-18.SXF
+ c6msfc3-jsv-mz.122-14.SX2
Products Confirmed Not Vulnerable
+--------------------------------
* Systems that are running in Native Mode without Cisco
IOS
Software Modularity are not affected.
* Systems without an MSFC2, MSFC2a or MSFC3 are not
affected.
No other Cisco products are known to be affected by this
vulnerability.
Details
=======
Cisco IOS Software Modularity combines subsystems into
individual
processes and enhances the Cisco IOS Software memory
architecture to
provide process-level fault isolation and subsystem "In
Service
Software Upgrade" (ISSU) capability. These enhancements
are delivered
in Cisco IOS Software for the Catalyst 6500 Series
Supervisor Engine
720 and Supervisor Engine 32. Cisco IOS Software Modularity
was first
delivered as an option in a Cisco IOS Software Release
12.2(18)SXF4.
More information on Modular IOS can be found at the
following URL:
http://www.cisco.com/en/
US/products/hw/switches/ps708/prod_bulletin0900aecd80313e15.
html
Not all 12.2(18)SXF4 images support Modular IOS. Only the
images with
a "-vz" in the image name support Modular IOS and
are affected by
this vulnerability. A conclusive list of all affected image
names
that support Cisco IOS Software Modularity is provided in
the
Affected Products section.
In Hybrid Mode, a CatOS image is used as the system software
to run
the Supervisor Engine on the Catalyst systems. If an MSFC
is
installed, a separate IOS Software image is used in order to
run the
MSFC. CatOS provides the Layer 2 (L2) switching
functionality. The
Cisco IOS on the MSFC provides the Layer 3 (L3) routing
functionality. It differs from the Native Mode, in which a
single
Cisco IOS Software image is used as the system software to
run both
the Supervisor Engine and MSFC on the Catalyst systems. IOS
software
that runs on MSFC in Hybrid Mode is also affected by this
vulnerability. More information about the differences
between Hybrid
and Native Modes can be found at the following URL:
http://www.cisco
.com/en/US/products/hw/switches/ps708/products_white_paper09
186a00800c8441.shtml
MPLS packets received by a Route Processor (MSFC) Layer 3
interface
can potentially trigger this vulnerability. The system in
question
does not need to be configured for MPLS to be vulnerable.
MPLS
packets can only be sent from the local network segment,
limiting the
scope of the exploitation.
This issue is documented in bug IDs CSCsd37415 ( registered
customers
only) and CSCef90002 ( registered customers only) .
Vulnerability Scoring Details
+----------------------------
Cisco is providing scores for the vulnerabilities in this
advisory
based on the Common Vulnerability Scoring System (CVSS).
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.
Cisco PSIRT will set the bias in all cases to normal.
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/in
telligence/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/c
vss.
CSCsd37415 - RP crashed on sending MPLS packet to a
interface
CVSS Base Score: 3.3
- - Access Vector: Remote
- - Access Complexity: Low
- - Authentication: Not Required
- - Confidentiality Impact: None
- - Integrity Impact: None
- - Availability Impact: Complete
- - Impact Bias: Normal
CVSS Temporal Score: 2.7
- - Exploitability: Functional
- - Remediation Level: Official Fix
- - Report Confidence: Confirmed
CSCef90002 - MSFC crashed due to corrupted program counter
CVSS Base Score: 3.3
- - Access Vector: Remote
- - Access Complexity: Low
- - Authentication: Not Required
- - Confidentiality Impact: None
- - Integrity Impact: None
- - Availability Impact: Complete
- - Impact Bias: Normal
CVSS Temporal Score: 2.7
- - Exploitability: Functional
- - Remediation Level: Official Fix
- - Report Confidence: Confirmed
Impact
======
Successful exploitation of the vulnerability may result in
the reload
of the system on systems that are running with Cisco IOS
Software
Modularity and the reload of MSFC on systems that are
running in
Hybrid Mode.
Repeated exploitation may lead to a denial of service
condition.
Software Version 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 that
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.
Each row of the Cisco IOS software table (below) describes a
release
train and the platforms or products for which it is
intended. If a
given release train is vulnerable, then the earliest
possible
releases that contain the fix (the "First Fixed
Release") and the
anticipated date of availability for each are listed in the
"Rebuild"
and "Maintenance" columns. A device running a
release in the given
train that is earlier than the release in a specific column
(less
than the First Fixed Release) is known to be vulnerable. The
release
should be upgraded at least to the indicated release or a
later
version (greater than or equal to the First Fixed Release
label).
For more information on the terms "Rebuild" and
"Maintenance,"
consult the following URL:
http://w
ww.cisco.com/warp/public/620/1.html.
+---------------------------------------+
| | Availability of Fixed |
| Trains | Releases |
| |-----------------------------|
| | Rebuild | Maintenance |
|---------+-----------------------------|
| 12.1E | Not vulnerable |
|---------+-----------------------------|
| 12.2SXA | Vulnerable. Migrate to 12.2 |
| | (17d)SXB5 or later |
|---------+-----------------------------|
| 12.2SXB | 12.2(17d)SXB5 | |
|---------+---------------+-------------|
| 12.2SXD | 12.2(18)SXD3 | |
|---------+-----------------------------|
| 12.2SXE | Not vulnerable |
|---------+-----------------------------|
| 12.2SXF | 12.2(18)SXF5 | |
| (*) | | |
+---------------------------------------+
* Only 12.2(18)SXF4 with IOS Software Modularity is
affected. 12.2SXF
releases that run in Hybrid Mode are not affected. Please
see the
Affected Products section for more information.
A special patch for 12.2(18)SXF4 with Cisco IOS Software
Modularity
is also available.
Patch Name: MA0045
Image Name: s72033-AMA0045-patch.122-18.SXF4
The above patch can be downloaded from the Cisco IOS
Software
Modularity Patch Navigator at
http:/
/tools.cisco.com/swdf/ionpn/jsp/main.jsp
Workarounds
===========
There are no workarounds for this vulnerability.
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
-20070228-mpls.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.
This vulnerability was reported by a customer.
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-2
0070228-mpls.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-February-28 | 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/produ
cts/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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