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Category:   Device (Firewall)  >   Cisco Firewall Services Module Vendors:   Cisco
Cisco Firewall Services Module Protocol Independent Multicast (PIM) Processing Error Lets Remote Users Deny Service
SecurityTracker Alert ID:  1026798
SecurityTracker URL:
CVE Reference:   CVE-2012-0356   (Links to External Site)
Date:  Mar 14 2012
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): Cisco Catalyst 6500 Series FWSM; 3.1, 3.2, 4.0, 4.1
Description:   A vulnerability was reported in Cisco Firewall Services Module. A remote user can cause denial of service conditions.

A remote user can send a specially crafted Protocol Independent Multicast (PIM) message to cause the target device to reload. Devices with multicast routing enabled are affected.

Cisco has assigned Cisco bug ID CSCtu97367 to this vulnerability.

Impact:   A remote user can cause the target device to reload.
Solution:   The vendor has issued a fix (3.2(23), 4.1(8)).

The vendor's advisory is available at:

Vendor URL: (Links to External Site)
Cause:   State error

Message History:   None.

 Source Message Contents

Subject:  Cisco Security Advisory: Cisco Firewall Services Module Crafted Protocol Independent Multicast Message Denial of Service Vulnerability

Hash: SHA256

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)


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

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:

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

A separate Cisco Security Advisory has been published to disclose the
vulnerabilities that affect the ASA and ASASM. That advisory is
available at:

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        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.


The following section gives additional details about this

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

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:

Cisco has also provided a CVSS calculator to compute the environmental
impact for individual networks at the following link:

* 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


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:

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)            |


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
Or as set forth at:

Do not contact or 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 at:

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:

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:
For additional TAC contact information, including localized telephone
numbers, instructions, and e-mail addresses for support in various

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


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.


This advisory is posted on Cisco Security Intelligence Operations at
the following link:

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


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

Revision History

| 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 at:
This web page includes instructions for press inquiries regarding
Cisco Security Advisories. All Cisco Security Advisories are available

Copyright 2010-2011 Cisco Systems, Inc. All rights reserved.
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