[c-nsp] Cisco Security Advisory: Cisco Unified Communications Manager Denial of Service Vulnerabilities

Wed Aug 24 12:05:36 EDT 2011

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://www.cisco.com/warp/public/707/cisco-sa-20110824-cucm.shtml

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://www.cisco.com/warp/public/707/cisco-sa-20110824-ime.shtml

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://www.cisco.com/warp/public/707/cisco-sa-20110824-ime.shtml

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

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

* CSCtf97162 - CCM Application Restarts During TCP Flood

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

* CSCtc61990 - Coredump may be experienced when processing 
  certain SIP packets

CVSS Base Score - 7.1
    Access Vector -            Network
    Access Complexity -        Medium
    Authentication -           None
    Confidentiality Impact -   None
    Integrity Impact -         None
    Availability Impact -      Complete

CVSS Temporal Score - 5.9
    Exploitability -           Functional
    Remediation Level -        Official-Fix
    Report Confidence -        Confirmed

*  CSCth43256 - Coredump may be experienced when processing
   certain SIP packets

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

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

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

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

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. 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      | Recommended |
| Communications Manager  |  Releases   |
|         Version         |             |
|-------------------------+-------------|
| 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/admin/7_1_2/ccmcfg/b03dpi.html#wp1075124

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://www.cisco.com/warp/public/707/cisco-amb-20110824-cucm-ime.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 at cisco.com or security-alert at 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 at 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://www.cisco.com/warp/public/707/cisco-sa-20110824-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 at cisco.com
  * first-bulletins at lists.first.org
  * bugtraq at securityfocus.com
  * vulnwatch at vulnwatch.org
  * cisco at spot.colorado.edu
  * cisco-nsp at puck.nether.net
  * full-disclosure at lists.grok.org.uk
  * comp.dcom.sys.cisco at 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      | 2011-August-24 | 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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