Advisory ID: cisco-sa-20100825-cucm
For Public Release 2010 August 25 16:00 UTC (GMT)
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 software updates that address these vulnerabilities. There are no workarounds for these vulnerabilities.
This advisory is posted at
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
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.
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.
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:
Cisco has also provided a CVSS calculator to help compute
the environmental impact for individual networks at:
CSCtd17310 - potential core dump issue in
registered customers only)
Calculate the environmental score of
CVSS Base Score - 7.8
CVSS Temporal Score - 6.4
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.
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
Cisco Unified Communication Manager Version
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
There are no workarounds for the vulnerabilities described in this
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:
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:
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:
Cisco has released 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 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 vulnerabilities described in this advisory.
All vulnerabilities described in this advisory were discovered as a
result of internal testing conducted by Cisco.
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.
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.