Advisory ID: cisco-sa-20090923-cm
For Public Release 2009 September 23 16:00 UTC (GMT)
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 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
Individual publication links are in "Cisco Event Response:
Semiannual Cisco IOS Software Advisory Bundled Publication" at the following
The vulnerability described in this document applies to the Cisco
Unified Communications Manager.
The following Cisco Unified Communications Manager versions are
Cisco Unified Communications Manager 5.x versions prior to
Cisco Unified Communications Manager 6.x versions prior to
Cisco Unified Communications Manager 7.0.x versions prior to
Cisco Unified Communications Manager 7.1.x versions prior to
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
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
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:
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 vulnerability.
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
This vulnerability is documented in Cisco bug ID
registered customers only)
and has been assigned
Common Vulnerabilities and Exposures (CVE) ID CVE-2009-2864.
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
Calculate the environmental score of
CVSS Base Score - 7.8
CVSS Temporal Score - 6.4
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.
When considering software upgrades, also consult
and any subsequent advisories to determine exposure and a complete upgrade
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 vulnerable.
First Fixed Version
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
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 interface.
Step 2 Navigate to System >
Cisco Unified CM and locate the appropriate Cisco Unified
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 location:
Cisco has released software updates that address this vulnerability. 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 firstname.lastname@example.org or email@example.com
for software upgrades.
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
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 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 obtain software patches and bug fixes 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)
Customers should have the product serial number available and be prepared to provide the URL of this notice as evidence of entitlement to a software patch or bug fix. Customers without service contracts should request a software patch or bug fix through the TAC.
for additional TAC contact information, including localized telephone numbers,
and instructions and e-mail addresses for use in various languages.
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
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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.
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.
Initial public release