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Cisco Security Advisory

Cisco Unified Communications Manager Denial of Service Vulnerabilities

Advisory ID: cisco-sa-20110824-cucm

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110824-cucm

Revision 1.2

Last Updated  2011 October 26 16:36  UTC (GMT)

For Public Release 2011 August 24 16:00  UTC (GMT)


Summary

Cisco Unified Communications Manager contains five (5) denial of service (DoS) vulnerabilities.

Cisco has released free software updates for affected versions of Cisco Unified Communications Manager to address the vulnerabilities. A workaround exists for the SIP and Packet Capture Service DoS vulnerabilities.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110824-cucm.

Two of the vulnerabilities described in this advisory also affect the Cisco Intercompany Media Engine.

A separate Cisco Security Advisory has been published to disclose the vulnerabilities that affect the Cisco Intercompany Media Engine. That advisory is available at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110824-ime.


Affected Products

Vulnerable Products

The following products are affected by at least one of the vulnerabilities that are described in this advisory:

  • Cisco Unified Communications Manager 4.x
  • Cisco Unified Communications Manager 6.x
  • Cisco Unified Communications Manager 7.x
  • Cisco Unified Communications Manager 8.x

Note: Cisco Unified Communications Manager version 5.1 reached end of software maintenance on February 13, 2010. Customers who are using Cisco Unified Communications Manager 5.x versions should contact their Cisco support team for assistance in upgrading to a supported version of Cisco Unified Communications Manager.


Products Confirmed Not Vulnerable

All supported versions of Cisco Unified Communications Manager are affected by one or more of the vulnerabilities described in this advisory.

Details

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.

DoS Vulnerabilities

Cisco Unified Communications Manager contains five DoS vulnerabilities that could cause a critical process to fail, resulting in disruption of voice services.

The first DoS vulnerability involves the Packet Capture Service which is enabled by default. The Packet Capture Service fails to timeout or close idle TCP connections. It is possible for a remote attacker to exhaust the Cisco Unified Communications Manager's memory by opening multiple connections, which will cause Cisco Unified Communications Manager to restart. The Packet Capture Service should be disabled in the Cisco Unified Communications Manager Administration Interface by setting the service parameter to False. The Cisco Unified Communications Manager application must be restarted for the change to take effect. This vulnerability is documented in Cisco Bug ID CSCtf97162 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) identifier CVE-2011-2560. This vulnerability affects only 4.x versions of Cisco Unified Communications Manager.

The second DoS vulnerability involves certain configurations of Media Termination Points (MTP). One-way audio may be observed when an MTP is configured with the g729ar8 codec only. In certain situations, an interruption in service may occur and a stack trace will be generated by the Session Initiation Protocol (SIP) process when processing the Session Description Protocol SDP portion of a SIP call. This vulnerability is documented in Cisco Bug ID CSCtc61990 ( registered customers only) and has been assigned CVE identifier CVE-2011-2561. This vulnerability applies only to Cisco Unified Communications Manager versions 7.0(x) and later and is fixed in versions 7.1(5b)su4 and 8.0(1).

The third DoS vulnerability involves a coredump when processing certain SIP INVITE messages. This vulnerability is documented in Cisco Bug ID CSCth43256 ( registered customers only) and has been assigned CVE identifier CVE-2011-2562. This vulnerability affects Cisco Unified Communications Manager version 6.x and later and is fixed in Cisco Unified Communications Manager versions 6.1(5)su2, 7.1(5b)su3, 8.0(3a)su1 and 8.5(1).

The remaining two DoS vulnerabilities involve the Service Advertisement Framework (SAF). An unauthenticated attacker could exploit these vulnerabilities by sending crafted SAF packets to an affected device. Successful exploitation could cause the device to reload. These vulnerabilities are documented in Cisco Bug IDs CSCth26669 ( registered customers only) and CSCth19417 ( registered customers only) and have been assigned CVE identifiers CVE-2011-2563 and CVE-2011-2564, respectively. These vulnerabilities affect Cisco Unified Communications Manager 8.x and are fixed in Cisco Unified Communications Manager versions 8.5(1). Cisco Intercompany Media Engine Release 8.x is also affected by these vulnerabilities. A separate Cisco Security Advisory has been published to disclose the vulnerabilities that affect the Cisco Intercompany Media Engine. That advisory is available at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110824-ime.

Note: An established TCP connection with a three-way handshake is required to trigger the SAF vulnerabilities.


Vulnerability Scoring Details

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 .

CSCtf97162 - CCM Application Restarts During TCP Flood

Calculate the environmental score of CSCtf97162

CVSS Base Score - 7.8

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Low

None

None

None

Complete

CVSS Temporal Score - 6.4

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

CSCtc61990 - Coredump may be experienced when processing certain SIP packets

Calculate the environmental score of CSCtc61990

CVSS Base Score - 7.1

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Medium

None

None

None

Complete

CVSS Temporal Score - 5.9

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

CSCth43256 - Coredump may be experienced when processing certain SIP packets

Calculate the environmental score of CSCth43256

CVSS Base Score - 7.8

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Low

None

None

None

Complete

CVSS Temporal Score - 6.4

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

CSCth26669 - CUCM may experience a reload when receiving certain UCM client msgs

Calculate the environmental score of CSCth26669

CVSS Base Score - 7.8

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Low

None

None

None

Complete

CVSS Temporal Score - 6.4

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

CSCth19417 - CUCM may experience a reload when receiving certain UCM client msgs

Calculate the environmental score of CSCth19417

CVSS Base Score - 7.8

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Low

None

None

None

Complete

CVSS Temporal Score - 6.4

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed


Impact

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

Software Versions 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 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.

Cisco recommends upgrading to a release equal to or later than the release in the Recommended Releases column of the table.

Cisco Unified Communications Manager Version

Recommended Releases

6.x

6.1(5)SU3

7.x

7.1(5b)SU4

8.0

8.0(3a)SU2

8.5

8.5(1)SU2, 8.6(1)



Workarounds

A workaround exists for the SIP DoS vulnerabilities. Cisco Unified Communications Manager versions 6.1(4), 7.1(2), and 8.0(1) introduced the ability to disable SIP processing. SIP processing is enabled by default. Customers who do not require SIP processing can use the following instructions to disable SIP processing:

  • Step 1: Log into the Cisco Unified Communications Manager Administration Interface.
  • Step 2: Navigate to System > Service Parameters and select the appropriate Cisco Unified Communications Manager server and the Cisco CallManager service.
  • Step 3: Change the SIP Interoperability Enabled parameter to False, and click Save. 

Note: For a SIP processing 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 document at the following location: http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/7_1_2/ccmcfg/b03dpi.html#wp1075124

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

A workaround exists for the DoS vulnerabilities involving the Packet Capture Service in Cisco Communications Manager version 4.x. Customers who do not require the Packet Capture Service for troubleshooting can use the following instructions to disable this process:

  • Step 1: Log into the Cisco Unified Communications Manager Administration web interface.
  • Step 2: Navigate to System > Service Parameters and select the appropriate Cisco Unified Communications Manager server and the Packet Capture Service.
  • Step 3: Change the Packet Capture Enabled parameter to False, and click Save. 

Note: For the Packet Capture Service 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 document at the following location: http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/service/4_2_3/ccmsrvs/sscontrl.html

Additional mitigations that can be deployed on Cisco devices in the network are available in the companion document "Cisco Applied Mitigation Bulletin: Identifying and Mitigating Exploitation of the Multiple Vulnerabilities in Cisco Unified Communications Manager" which is available at the following location:

http://tools.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20110824-cucm-ime


Obtaining Fixed Software

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 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 agreements 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 do not hold a Cisco service contract, and customers who purchase through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should acquire 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: tac@cisco.com

Customers should have their product serial number available and be prepared to give the URL of this notice as evidence of entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.

Refer to http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html for additional TAC contact information, including 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 vulnerabilities described in this advisory.

These vulnerabilities were found during internal testing and during the troubleshooting of customer service requests.

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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110824-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-teams@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.


Revision History

Initial public release

Revision 1.2

2011-October-26

Revision table updated

Revision 1.1

2011-October-21

Updated URL

Revision 1.0

2011-August-24

Initial 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/web/about/security/psirt/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.


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