Advisory ID: cisco-sa-20120314-fwsm
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120314-fwsm
Revision 1.1
Last Updated 2012 March 19 16:05 UTC (GMT)
For Public Release 2012 March 14 16:00 UTC (GMT)
Contents
Summary
Affected Products
Details
Vulnerability Scoring Details
Impact
Software Versions and Fixes
Workarounds
Obtaining Fixed Software
Exploitation and Public Announcements
Status of this Notice: Final
Distribution
Revision History
Cisco Security Procedures
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 may be workarounds that mitigate this vulnerability. See the "Workarounds" section of this advisory. 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
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
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
Details
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 (registered customers only), and has been assigned Common Vulnerabilities and 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
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CSCtu97367 Calculate the environmental score of CSCtu97367 |
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|---|---|---|---|---|---|---|
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CVSS Base Score - 7.8 |
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Access Vector |
Access Complexity |
Authentication |
Confidentiality Impact |
Integrity Impact |
Availability Impact |
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Network |
Low |
None |
None |
None |
Complete |
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CVSS Temporal Score - 6.4 |
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Exploitability |
Remediation Level |
Report Confidence |
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Functional |
Official-Fix |
Confirmed |
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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 and 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 Release |
First Fixed Release |
| Protocol Independent Multicast Denial of Service Vulnerability |
2.2 |
Not Affected |
| 2.3 |
Not Affected |
|
| 3.1 |
Vulnerable: Migrate to 3.2 |
|
| 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
If PIM is required to be enabled, there are no workarounds that mitigate this vulnerability. However, if multicast routing is required but PIM is not used on an interface, PIM can be disabled on the Cisco FWSM interfaces by issuing the no pim interface-level command.
The following example shows the Vlan20 interface, configured as outside, on a Cisco FWSM device with PIM disabled:
interface Vlan20
nameif outside
security-level 0
ip address 192.168.1.1 255.255.255.0
no pim
To verify that PIM is disabled on all interfaces, issue the show pim interface command and make sure that for all interfaces the PIM state is set to off. The following example shows a Cisco FWSM with PIM disabled on all interfaces.
fwsm# show pim interface
Address Interface PIM Nbr Hello DR DR
Count Intvl Prior
192.168.1.1 outside off 0 30 1 not elected
172.16.1.66 inside off 0 30 1 not elected
Obtaining Fixed Software
Cisco has released free software updates that address the vulnerability 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@cisco.com or security-alert@cisco.com for software upgrades.
Customers with Service Contracts
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@cisco.com
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@cisco.com
- first-bulletins@lists.first.org
- bugtraq@securityfocus.com
- vulnwatch@vulnwatch.org
- cisco@spot.colorado.edu
- cisco-nsp@puck.nether.net
- full-disclosure@lists.grok.org.uk
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
| Revision 1.1 | 2012-March-19 | "Workarounds" section: Added a workaround for when PIM is not in use |
| Revision 1.0 | 2012-March-14 | Initial public release |