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Cisco Security Advisory: Cisco Unified Communications Manager Denial
of Service Vulnerabilities

Advisory ID: cisco-sa-20100825-cucm

Revision 1.0

For Public Release 2010 August 25 1600 UTC (GMT)

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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://www.cisco.com/warp/public/707/cisco-sa-20100825-cucm.shtml

Affected Products
=================

Vulnerable Products
+------------------

The following products are affected by vulnerabilities that are
described in this advisory:

  * Cisco Unified Communications Manager 6.x
  * Cisco Unified Communications Manager 7.x
  * Cisco Unified Communications Manager 8.x

Products Confirmed Not Vulnerable
+--------------------------------

Cisco Unified Communications Manager version 4.x is not affected by
these vulnerabilities. No other Cisco products are currently known to
be affected by these vulnerabilities.

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.

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.

Vulnerability Scoring Details
=============================

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

CSCtd17310 - potential core dump issue in SIPStationInit code

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

CSCtf66305 - CCM Coredump From SendCombinedStatusInfo on
Fuzzed REGISTER Message

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

Impact
======

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.

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 Unified      | Recommended |
|  Communication Manager  |   Release   |
|         Version         |             |
|-------------------------+-------------|
| 6.x                     | 6.1(5)SU1   |
|-------------------------+-------------|
| 7.x                     | 7.1(5b)SU2  |
|-------------------------+-------------|
| 8.x                     | 8.0(3a)     |
+---------------------------------------+

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

Workarounds
===========

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://www.cisco.com/warp/public/707/cisco-amb-20100825-cucm-cup.shtml

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.

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

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://www.cisco.com/warp/public/707/cisco-sa-20100825-cucm.shtml

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.

Revision History
================

+---------------------------------------+
| Revision |                | Initial   |
| 1.0      | 2010-August-25 | 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/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
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