[Full-disclosure] Cisco Security Advisory: Cisco Firewall Services Module Crafted Protocol Independent Multicast Message Denial of Service Vulnerability



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Cisco Firewall Services Module Crafted Protocol Independent Multicast
Message Denial of Service Vulnerability

Advisory ID: cisco-sa-20120314-fwsm

Revision 1.0

For Public Release 2012 March 14 16:00 UTC (GMT)
+---------------------------------------------------------------------


Summary
=======

The Cisco Catalyst 6500 Series Firewall Services Module (FWSM)
contains a Protocol Independent Multicast (PIM) Denial of Service
Vulnerability.

Cisco has released free software updates that address this
vulnerability. There are no workarounds available that mitigate this
vulnerability. This advisory is available at the following link:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120314-fwsm

Note: The Cisco Adaptive Security Appliance (ASA) and the Cisco
Catalyst 6500 ASA Services Module (ASASM) are also affected by this
vulnerability.

A separate Cisco Security Advisory has been published to disclose the
vulnerabilities that affect the ASA and ASASM. That advisory is
available at:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120314-asa

Affected Products
=================

The Cisco Catalyst 6500 Series Firewall Services Module is affected by
this vulnerability. Not all versions of released FWSM Software are
affected. Consult the "Software Versions and Fixes" section of this
security advisory for more information.


Vulnerable Products
- -------------------

For specific version information, refer to the "Software Versions and
Fixes" section of this advisory.

Protocol Independent Multicast Denial of Service Vulnerability
+-------------------------------------------------------------

The Cisco FWSM is affected by a vulnerability that may cause affected
devices to reload during the processing of a PIM message when
multicast routing is enabled. Multicast routing is disabled by
default, however when multicast routing is enabled on the Cisco FWSM,
PIM is automatically enabled on all interfaces. The following command
enables multicast routing:

fwsm(config)# multicast-routing

To verify whether PIM is enabled on an interface use the show pim
interface command. The following example shows PIM enabled on the
"inside" interface:

fwsm# sh pim interface

Address Interface PIM Nbr Hello DR DR
Count Intvl Prior

172.16.1.66 inside on 0 30 1 this system


Products Confirmed Not Vulnerable
+--------------------------------

With the exception of the Cisco ASA and the Cisco Catalyst 6500 ASA
Services Module, no other Cisco products are currently known to be
affected by this vulnerability.


Details
=======

The following section gives additional details about this
vulnerability.


Protocol Independent Multicast Denial of Service Vulnerability
+-------------------------------------------------------------

Multicast routing is a bandwidth-conserving technology that reduces
traffic by simultaneously delivering a single stream of information to
multiple recipients.

Protocol Independent Multicast (PIM) is a multicast routing protocol
that is independent of any IP routing protocol. PIM can leverage any
unicast routing protocols that are in use, including Exterior Gateway
Routing Protocol (EIGRP), Open Shortest Path First (OSPF), Border
Gateway Protocol (BGP), or static routes, to populate the unicast
routing table. PIM uses this unicast routing information to perform
the multicast forwarding function, and is IP protocol-independent.
Although PIM is called a multicast routing protocol, it actually uses
the unicast routing table to perform the Reverse Path Forwarding (RPF)
check function instead of building a completely independent multicast
routing table. PIM does not send or receive multicast routing updates
between routers as do other routing protocols.

A vulnerability exists in the way PIM is implemented that may cause
affected devices to reload during the processing of a PIM message when
multicast routing is enabled. The vulnerability is due to improper
handling of PIM messages. An attacker could exploit this vulnerability
by sending a crafted PIM message to the affected system.


This vulnerability is documented in Cisco bug ID CSCtu97367, and has
been assigned Common Vulnerabilities ans Exposures (CVE) ID
CVE-2012-0356.


Vulnerability Scoring Details
=============================

Cisco has scored the vulnerability in this advisory based on the
Common Vulnerability Scoring System (CVSS). The CVSS scoring in this
security advisory is in accordance with CVSS version 2.0.

CVSS is a standards-based scoring method that conveys vulnerability
severity and helps organizations determine the urgency and priority of
a response.

Cisco has provided a base and temporal score. Customers can also
compute environmental scores that help determine the impact of the
vulnerability in their own networks.

Cisco has provided additional information regarding CVSS at the
following link:
http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html

Cisco has also provided a CVSS calculator to compute the environmental
impact for individual networks at the following link:
http://intellishield.cisco.com/security/alertmanager/cvss

* CSCtu97367 - Protocol-Independent Multicast Denial of Service Vulnerability

CVSS Base Score - 7.8
Access Vector - Network
Access Complexity - Low
Authentication - None
Confidentiality Impact - None
Integrity Impact - None
Availability Impact - Complete

CVSS Temporal Score - 6.4
Exploitability - Functional
Remediation Level - Official-Fix
Report Confidence - Confirmed


Impact
======

Protocol Independent Multicast Denial of Service Vulnerability

Successful exploitation of the vulnerability may allow a remote,
unauthenticated attacker to cause the affected system to reload.


Software Versions and Fixes
===========================

When considering software upgrades, customers are advised to consult
the Cisco Security Advisories and Responses archive at:
http://www.cisco.com/go/psirt

Customers should review subsequent advisories to determine exposure
and a complete upgrade solution.

In all cases, customers should ensure that the devices to be upgraded
contain sufficient memory and confirm that current hardware and
software configurations will continue to be supported properly by the
new release. If the information is not clear, customers are advised to
contact the Cisco Technical Assistance Center (TAC) or their
contracted maintenance providers.


Protocol Independent Multicast Denial of Service Vulnerability
+-------------------------------------------------------------

+-------------------------------------------------------------------+
| Vulnerability | Major | First Fixed |
| | Release | Release |
|------------------------------------+---------+--------------------|
| | 2.2 | Not Affected |
| |---------+--------------------|
| | 2.3 | Not Affected |
| |---------+--------------------|
| | 3.1 | Vulnerable: |
| | | Migrate to 3.2 |
|Protocol Independent Multicast |---------+--------------------|
| Denial of Service Vulnerability | 3.2 | 3.2(23) Available |
| | | late March 2012 |
| |---------+--------------------|
| | 4.0 | Vulnerable: |
| | | Migrate to 4.1 |
| |---------+--------------------|
| | 4.1 | 4.1(8) |
+-------------------------------------------------------------------+


Workarounds
===========

Protocol Independent Multicast Denial of Service Vulnerability

There are no workarounds that mitigate this vulnerability.


Obtaining Fixed Software
========================

Cisco has released free software updates that address the
vulnerabilities described in this advisory. Prior to deploying
software, customers are advised to consult their maintenance providers
or check the software for feature set compatibility and known issues
that are specific to their environments.

Customers may only install and expect support for feature sets they
have purchased. By installing, downloading, accessing, or otherwise
using such software upgrades, customers agree to follow the terms of
the Cisco software license at
http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html
Or as set forth at:
http://www.cisco.com/public/sw-center/sw-usingswc.shtml

Do not contact psirt@xxxxxxxxx or security-alert@xxxxxxxxx for
software upgrades.


Customers with Service Contracts
+-------------------------------

Customers with contracts should obtain upgraded software through their
regular update channels. For most customers, upgrades should be
obtained through the Software Center on Cisco.com at:
http://www.cisco.com


Customers Using Third-Party Support Organizations
+------------------------------------------------

Customers with Cisco products that are provided or maintained through
prior or existing agreements with third-party support organizations,
such as Cisco Partners, authorized resellers, or service providers,
should contact that organization for assistance with the appropriate
course of action.

The effectiveness of any workaround or fix depends on specific
customer situations, such as product mix, network topology, traffic
behavior, and organizational mission. Because of the variety of
affected products and releases, customers should consult their service
providers or support organizations to ensure that any applied
workaround or fix is the most appropriate in the intended network
before it is deployed.


Customers Without Service Contracts
+----------------------------------

Customers who purchase directly from Cisco but do not hold a Cisco
service contract and customers who make purchases through third-party
vendors but are unsuccessful in obtaining fixed software through their
point of sale should obtain upgrades by contacting the Cisco Technical
Assistance Center (TAC):

* +1 800 553 2447 (toll free from within North America)
* +1 408 526 7209 (toll call from anywhere in the world)
* e-mail: tac@xxxxxxxxx

Customers should have the product serial number available and be
prepared to provide the URL of this advisory as evidence of
entitlement to a free upgrade. Customers without service contracts
should request free upgrades through the TAC.

Refer to Cisco Worldwide Contacts at:
http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html
For additional TAC contact information, including localized telephone
numbers, instructions, and e-mail addresses for support in various
languages.


Exploitation and Public Announcements
=====================================

The Cisco Product Security Incident Response Team (PSIRT) is not aware
of any public announcements or malicious use of the vulnerability that
is described in this advisory.

The vulnerability described in this security advisory was found during
the resolution of a customer support case.


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 Security Intelligence Operations at
the following link:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120314-fwsm

Additionally, a text version of this advisory is clear signed with the
Cisco PSIRT PGP key and circulated among the following e-mail
addresses:

* cust-security-announce@xxxxxxxxx
* first-bulletins@xxxxxxxxxxxxxxx
* bugtraq@xxxxxxxxxxxxxxxxx
* vulnwatch@xxxxxxxxxxxxx
* cisco@xxxxxxxxxxxxxxxxx
* cisco-nsp@xxxxxxxxxxxxxxx
* full-disclosure@xxxxxxxxxxxxxxxxx

Future updates of this advisory, if any, will reside on Cisco.com but
may not be announced on mailing lists. Users can monitor this
advisory's URL for any updates.


Revision History
================

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| Revision 1.0 | 2012-March-14 | Initial public release |
+-------------------------------------------------------------------+


Cisco Security Procedures
=========================

Complete information about reporting security vulnerabilities in Cisco
products, obtaining assistance with security incidents, and
registering to receive security information from Cisco is available on
Cisco.com at:
http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html
This web page includes instructions for press inquiries regarding
Cisco Security Advisories. All Cisco Security Advisories are available
at:
http://www.cisco.com/go/psirt

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