[apops] Cisco Security Advisory: Cisco Unified Communications Manager Se

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  • Subject: [apops] Cisco Security Advisory: Cisco Unified Communications Manager Session Initiation Protocol Denial of Service Vulnerability
  • From: Cisco Systems Product Security Incident Response Team <psirt at cisco dot com>
  • Date: Wed, 23 Sep 2009 12:15:00 -0400
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      Cisco Security Advisory: Cisco Unified Communications Manager Session
      Initiation Protocol Denial of Service Vulnerability
      Advisory ID: cisco-sa-20090923-cm
      Revision 1.0
      For Public Release 2009 September 23
      Cisco Unified Communications Manager, which was formerly Cisco
      Unified CallManager, contains a denial of service (DoS) vulnerability
      in the Session Initiation Protocol (SIP) service. An exploit of this
      vulnerability may cause an interruption in voice services.
      Cisco has released free software updates that address this
      vulnerability. There are no workarounds for this vulnerability.
      This advisory is posted at:
      Note: Cisco IOS® Software is also affected by the vulnerability
      described in this advisory. A companion advisory for Cisco IOS
      software is available at:
      Note: The September 23, 2009, Cisco IOS Security Advisory bundled
      publication includes eleven Security Advisories. Ten of the
      advisories address vulnerabilities in Cisco IOS Software, and one
      advisory addresses a vulnerability in Cisco Unified Communications
      Manager. Each advisory lists the releases that correct the
      vulnerability or vulnerabilities detailed in the advisory. The
      following table lists releases that correct all Cisco IOS Software
      vulnerabilities that have been published on September 23, 2009, or
      Individual publication links are in "Cisco Event Response: Semiannual
      Cisco IOS Software Advisory Bundled Publication" at the following
      Affected Products
      The vulnerability described in this document applies to the Cisco
      Unified Communications Manager.
      Vulnerable Products
      The following Cisco Unified Communications Manager versions are
        * Cisco Unified Communications Manager 5.x versions prior to 5.1(3g)
        * Cisco Unified Communications Manager 6.x versions prior to 6.1(4)
        * Cisco Unified Communications Manager 7.0.x versions prior to 7.0(2a)su1
        * Cisco Unified Communications Manager 7.1.x versions prior to 7.1(2)
      Cisco Unified CallManager versions 4.x are not affected by this
      vulnerability. Administrators of systems that are running Cisco
      Unified Communications Manager versions 5.x, 6.x and 7.x can
      determine the software version by viewing the main page of the Cisco
      Unified Communications Manager Administration interface. The software
      version can also be determined by running the "show version active"
      command via the command-line interface.
      A SIP trunk must be configured for the Cisco Unified CallManager
      server to begin listening for SIP messages on TCP and UDP port 5060
      and TCP/5061. However, in Cisco Unified Communications Manager
      versions 5.x and later, the use of SIP as a call signaling protocol
      is enabled by default and cannot be disabled.
      Cisco IOS Software is also affected by this vulnerability, but it is
      associated with different Cisco bug IDs. A companion security
      advisory for Cisco IOS Software is available at:
      Products Confirmed Not Vulnerable
      Cisco Unified CallManager versions 4.x are not affected by this
      vulnerability. With the exception of Cisco IOS software, no other
      Cisco products are currently known to be affected by this
      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, voice-over-IP gateways, and
      multimedia applications.
      SIP is a popular signaling protocol that manages voice and video
      calls across IP networks such as the Internet. SIP is responsible for
      handling all aspects of call setup and termination. Voice and video
      are the most popular types of sessions that SIP handles, but the
      protocol is flexible enough to accommodate other applications that
      require call setup and termination. SIP call signaling can use UDP
      (port 5060), TCP (port 5060), or Transport Layer Security (TLS; TCP
      port 5061) as the underlying transport protocol.
      A DoS vulnerability exists in the SIP implementation of the Cisco
      Unified Communications Manager. This vulnerability could be triggered
      when Cisco Unified Communications Manager processes crafted SIP
      messages. An exploit could lead to a reload of the main Cisco Unified
      Communications Manager process.
      This vulnerability is documented in Cisco bug ID CSCsz95423 and has been
      assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2009-2864.
      Vulnerability Scoring Details
      Cisco has provided scores for the vulnerability 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:
      Cisco has also provided a CVSS calculator to help compute the
      environmental impact for individual networks at:
      CSCsz95423 - Crafted SIP packet may cause CM process to crash
      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
      Successful exploitation of the vulnerability that is described in
      this advisory could result in a reload of the Cisco Unified
      Communications Manager process, which may result in the interruption
      of voice services.
      Software Versions and Fixes
      When considering software upgrades, also consult:
      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.
      The following table contains the first fixed software release for
      this vulnerability. A device running a version of the given release
      in a specific row (less than the First Fixed Release) is known to be
      | Release   | First Fixed Version       |
      | 4.x       | Not Vulnerable            |
      | 5.x       | 5.1(3g)                   |
      | 6.x       | 6.1(4)                    |
      | 7.0.x     | 7.0(2a)su1                |
      | 7.1.x     | 7.1(2)                    |
      There are no workarounds for this vulnerability.
      It is possible to mitigate this vulnerability by implementing
      filtering on screening devices and permitting TCP/UDP access to ports
      5060 and TCP/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 CallManager Administration web
      Step 2 Navigate to System > Cisco Unified CM and locate the
      appropriate Cisco Unified Communications Manager.
      Step 3 Change the fields SIP Phone Port and SIP Phone Secure Port
      fields to a non standard port and click Save.
      SIP Phone Port, which is 5060 by default, refers to the TCP and UDP
      ports where the Cisco Unified Communications Manager listens for
      normal SIP messages, and SIP Phone Secure Port, by default 5061,
      refers to the TCP port where the Cisco Unified Communications Manager
      listens for SIP over 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:
      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 document at:
      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
      Denial of Service Vulnerabilities in Cisco Unified Communications
      Manager and Cisco IOS Software", which is available at the following
      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:
      or as otherwise set forth at Cisco.com Downloads at:
      Do not contact psirt at cisco dot com or security-alert at cisco dot 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 at cisco dot 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:
      for additional TAC contact information, including localized telephone
      numbers, and instructions and e-mail addresses for use in various
      Exploitation and Public Announcements
      The Cisco PSIRT is not aware of any public announcements or malicious
      use of the vulnerability described in this advisory.
      This vulnerability was discovered during internal testing.
      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's worldwide website at:
      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 at cisco dot com
        * first-bulletins at lists dot first dot org
        * bugtraq at securityfocus dot com
        * vulnwatch at vulnwatch dot org
        * cisco at spot dot colorado dot edu
        * cisco-nsp at puck dot nether dot net
        * full-disclosure at lists.grok dot org dot uk
        * comp.dcom.sys.cisco at newsgate dot cisco dot 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
      | Revision |                   | Initial |
      | 1.0      | 2009-September-23 | 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:
      This includes instructions for press inquiries regarding Cisco security
      notices. All Cisco security advisories are available at:
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