Cisco Security Advisory: Cisco Unified Communications Manager Session Initiation Protocol Denial of Service Vulnerabilities
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Cisco Security Advisory: Cisco Unified Communications Manager Session
Initiation Protocol Denial of Service Vulnerabilities
Advisory ID: cisco-sa-20080924-cucm
http://www.cisco.com/warp/public/707/cisco-sa-20080924-cucm.shtml
Revision 1.0
For Public Release 2008 September 24 1600 UTC (GMT)
- ---------------------------------------------------------------------
Summary
=======
Cisco Unified Communications Manager, formerly Cisco Unified
CallManager, contains two denial of service (DoS) vulnerabilities in
the Session Initiation Protocol (SIP) service. An exploit of these
vulnerabilities may cause an interruption in voice services.
Cisco will release free software updates that address these
vulnerabilities and this advisory will be updated as fixed software
becomes available. There are no workarounds for these
vulnerabilities.
Note: Cisco IOS software is also affected by the vulnerabilities
described in this advisory. A companion advisory for Cisco IOS
software is available at
http://www.cisco.com/warp/public/707/cisco-sa-20080924-sip.shtml
This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20080924-cucm.shtml
Affected Products
=================
The vulnerabilities described in this document apply to the Cisco
Unified Communications Manager.
Vulnerable Products
+------------------
The following Cisco Unified Communications Manager versions are
affected:
* Cisco Unified CallManager 4.1 versions prior to 4.1.3SR8
* Cisco Unified CallManager 4.2 versions prior to 4.2(3)SR4b
* Cisco Unified CallManager 4.3 versions prior to 4.3(2)SR1a
* Cisco Unified Communications Manager 5.x versions prior to 5.1
(3d)
* Cisco Unified Communications Manager 6.x versions prior to 6.1(2)
su1
Administrators of systems running Cisco Unified CallManager version
4.x can determine the software version by navigating to Help > About
Cisco Unified CallManager and selecting the Details button via the
Cisco Unified Communications Manager Administration interface.
Administrators of systems that are running Cisco Unified
Communications Manager versions 5.x and 6.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 command show version active via
the command line interface.
In Cisco Unified CallManager version 4.x, the use of SIP as a call
signaling protocol is not enabled by default, and for the Cisco
Unified CallManager server to start listening for SIP messages on TCP
and UDP ports 5060 and 5061 a SIP trunk needs to be configured.
In Cisco Unified Communications Manager versions 5.x and later, the
use of SIP as a call signaling protocol is enabled by default in
Cisco Unified Communications Manager and cannot be disabled.
Cisco IOS software is also affected by these vulnerabilities,
although they are tracked by different Cisco bug IDs. A companion
security advisory for Cisco IOS software is available at
http://www.cisco.com/warp/public/707/cisco-sa-20080924-sip.shtml
Products Confirmed Not Vulnerable
+--------------------------------
With the exception of Cisco IOS software, no other Cisco products are
currently known to be vulnerable to the issues described in this
advisory.
Cisco Unified Communications Manager version 7.x is not affected by
these vulnerabilities.
Cisco Unified CallManager version 4.x is not affected by these
vulnerabilities if it does not have any SIP trunks configured.
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, voice-over-IP gateways, and
multimedia applications.
SIP is a popular signaling protocol that is used to manage 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 to accommodate for other
applications that require call setup and termination. SIP call
signaling can use UDP (port 5060), TCP (port 5060), or TLS (TCP port
5061) as the underlying transport protocol.
Two DoS vulnerabilities exist in the SIP implementation of the Cisco
Unified Communications Manager. These vulnerabilities can be
triggered while processing specific and valid SIP messages and can
lead to a reload of the main Cisco Unified Communications Manager
process. Version 4.x of Cisco Unified CallManager do not have SIP
enabled by default unless a SIP trunk is configured. Versions 5.x and
later of the Cisco Unified Communications Manager have SIP is enabled
by default and cannot be disabled.
The vulnerabilities are being tracked by the following Cisco bug IDs:
* CSCsu38644, assigned CVE ID CVE-2008-3800
* CSCsm46064, assigned CVE ID CVE-2008-3801
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
CSCsu38644 - Valid SIP message can cause CCM process to crash
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
CSCsm46064 - Problem when CUCM sends out SIP message with valid header
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 described in this
advisory may result in a reload of the Cisco Unified Communications
Manager process, which could result in the interruption of voice
services.
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 CallManager version 4.1(3)SR8 contains fixes for all
vulnerabilities affecting Cisco Unified CallManager version 4.1
listed in this advisory, and is scheduled to be released in early
October 2008.
Cisco Unified CallManager version 4.2(3)SR4b contains fixes for all
vulnerabilities affecting Cisco Unified Communications Manager
version 4.2.x listed in this advisory, and is scheduled to be
released in early November 2008.
Cisco Unified CallManager version 4.3(2)SR1a contains fixes for all
vulnerabilities affecting Cisco Unified Communications Manager
version 4.3.x listed in this advisory, and is scheduled to be
released in early October 2008.
Cisco Unified Communications Manager version 5.1(3d) contains fixes
for all vulnerabilities affecting Cisco Unified Communications
Manager version 5.x listed in this advisory, and is scheduled to be
released in mid October 2008.
Cisco Unified Communications Manager version 6.1(2)SU1 contains fixes
for all vulnerabilities affecting Cisco Unified Communications
Manager version 6.x listed in this advisory, and is scheduled to be
released in mid October 2008.
Downloading Cisco Unified Communications Manager Software
+--------------------------------------------------------
To download Cisco Unified Communications Manager Software go to the
Voice Software Downloads section of the Software Center on cisco.com
at
http://tools.cisco.com/support/downloads/go/Redirect.x?mdfid=278875240
then navigate to IP Telephony > Call Control > Cisco Unified
Communications Manager (CallManager) and select the appropriate
version of Cisco Unified Communications Manager.
Workarounds
===========
There are no workarounds for these vulnerabilities.
It is possible to mitigate the vulnerabilities by implementing
filtering on screening devices. Permit TCP/UDP access to ports 5060
and 5061 from only networks that need SIP access to Cisco Unified
Communications Manager servers.
If the Cisco Unified Communications Manager does not need to provide
SIP services, the ports on which the Cisco Unified Communications
Manager listens for SIP messages can be moved to non-standard ports.
To change the ports from their default values, log into the Cisco
Unified CallManager Administration web interface, go to System >
Cisco Unified CM, locate the appropriate Cisco Unified Communications
Manager, change the fields SIP Phone Port and SIP Phone Secure Port
to a non-standard port, then click Save. SIP Phone Port, by default
5060, 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 and UDP ports 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
http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/admin/7_0_1/ccmcfg/b02ccm.html#wp1057513.
Note: For a change of the SIP ports to take effect, the Cisco
CallManager Service needs to be restarted. For information on how to
accomplish this, refer to "Restarting the Cisco CallManager Service"
at
http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/admin/7_0_1/ccmcfg/b03dpi.html#wp1075124
Additional mitigations that can be deployed on Cisco devices within
the network are available in the Cisco Applied Mitigation Bulletin
companion document for this advisory, which is available at the
following link:
http://www.cisco.com/warp/public/707/cisco-amb-20080924-sip.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/products/prod_warranties_item09186a008088e31f.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@xxxxxxxxx or security-alert@xxxxxxxxx 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@xxxxxxxxx
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/warp/public/687/Directory/DirTAC.shtml
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 vulnerability described in this advisory.
These vulnerabilities were discovered by Cisco internal testing and
during handling of customer service requests.
Status of this Notice: INTERIM
==============================
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. CISCO EXPECTS TO UPDATE THIS DOCUMENT AS NEW
INFORMATION BECOMES AVAILABLE.
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-20080924-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@xxxxxxxxx
* first-bulletins@xxxxxxxxxxxxxxx
* bugtraq@xxxxxxxxxxxxxxxxx
* vulnwatch@xxxxxxxxxxxxx
* cisco@xxxxxxxxxxxxxxxxx
* cisco-nsp@xxxxxxxxxxxxxxx
* full-disclosure@xxxxxxxxxxxxxxxxx
* comp.dcom.sys.cisco@xxxxxxxxxxxxxxxxxx
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 | 2008-September-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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