Cisco Security Advisory

Advisory ID: cisco-sa-20100825-cucm

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100825-cucm

Revision 1.0

For Public Release 2010 August 25 16:00  UTC (GMT)

Summary

Cisco Unified Communications Manager contains two denial of service (DoS) vulnerabilities that affect the processing of Session Initiation Protocol (SIP) messages. Exploitation of these vulnerabilities could cause an interruption of voice services.

Cisco has released free software updates that address these vulnerabilities. There are no workarounds for these vulnerabilities.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100825-cucm.

Affected Products

Cisco Unified Communications Manager is the call processing component of the Cisco IP Telephony solution that extends enterprise telephony features and functions to packet telephony network devices, such as IP phones, media processing devices, VoIP gateways, and multimedia applications.

Cisco Unified Communications Manager contains two DoS vulnerabilities that involve the processing of SIP messages. Each vulnerability is triggered by a malformed SIP message that could cause a critical process to fail, which could result in the disruption of voice services. All SIP ports (TCP ports 5060 and 5061, UDP ports 5060 and 5061) are affected.

The first SIP DoS vulnerability is documented in Cisco bug ID CSCtd17310 and has been assigned the CVE identifier CVE-2010-2837. This vulnerability is fixed in Cisco Unified Communications Manager versions 6.1(5)SU1, 7.0(2a)SU3, 7.1(3b)SU2, 7.1(5) and 8.0(1). Cisco Unified Communications Manager version 4.x is not affected.

The second SIP DoS vulnerability is documented in Cisco bug ID CSCtf66305 and has been assigned the CVE identifier CVE-2010-2838. The second vulnerability is fixed in Cisco Unified Communications Manager versions 7.0(2a)SU3, 7.1(5) and 8.0(3). Cisco Unified Communications Manager versions 4.x and 6.x are not affected.

Cisco has provided 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.

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

Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding CVSS at:

http://www.cisco.com/web/about/security/intelligence/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/cvss

Successful exploitation of the vulnerabilities that are described in this advisory could result in the interruption of voice services. Cisco Unified Communications Manager will restart the affected processes, but repeated attacks may result in a sustained DoS Condition.

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.

Note: The recommended releases listed in the table above are the latest Cisco Unified Communications Manager versions available at the publication of this advisory, and each release includes software fixes for all the vulnerabilities described in this advisory.

Cisco Unified Communications Manager software can be downloaded at the following link:

http://tools.cisco.com/support/downloads/go/Redirect.x?mdfid=268439621

There are no workarounds for the vulnerabilities described in this advisory.

It is possible to mitigate this vulnerability by implementing filtering on screening devices and permitting access to TCP ports 5060 and 5061 and to UDP ports 5060 and 5061 only from networks that require SIP access to Cisco Unified Communications Manager servers.

If Cisco Unified Communications Manager does not need to provide SIP services, administrators can configure the Cisco Unified Communications Manager to listen for SIP messages on non-standard ports. Use the following instructions to change the ports from their default values:

Step 1: Log into the Cisco Unified Communications Manager Administration web interface.

Step 2: Navigate to System > Cisco Unified CM and locate the appropriate Cisco Unified Communications Manager.

Step 3: Change the SIP Phone Port and SIP Phone Secure Port fields to a non-standard port and click Save.

The SIP Phone Port, which is set to 5060 by default, refers to the TCP and UDP ports on which the Cisco Unified Communications Manager listens for normal SIP messages. SIP Phone Secure Port, which is set to 5061 by default, refers to the TCP port on which the Cisco Unified Communications Manager listens for SIP over Transport Layer Security (TLS) messages. For additional information about this procedure, refer to the "Updating a Cisco Unified Communications Manager" section of the "Cisco Unified Communications Manager Administration Guide" at:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/admin/7_0_1/ccmcfg/b02ccm.html#wp1057513

Note: For a SIP port change to take effect, the Cisco CallManager Service must be restarted. For information on how to restart the service, refer to the "Restarting the Cisco CallManager Service" section of the administration guide at:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/admin/7_0_1/ccmcfg/b03dpi.html#wp1075124

Additional mitigation techniques that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory:

http://tools.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20100825-cucm-cup

Cisco has released free software updates that address these vulnerabilities. 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/en/US/docs/general/warranty/English/EU1KEN_.html , or as otherwise set forth at Cisco.com Downloads 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 Without Service Contracts

The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory.

All vulnerabilities described in this advisory were discovered as a result of internal testing conducted by Cisco.

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.

This advisory is posted on Cisco's worldwide website at:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100825-cucm

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-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
  
• comp.dcom.sys.cisco@newsgate.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.

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/products/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/go/psirt.