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

Wed Aug 26 12:00:00 EDT 2009

Cisco Unified Communications Manager (formerly CallManager) contains
multiple denial of service (DoS) vulnerabilities that if exploited
could cause an interruption to voice services. The Session Initiation
Protocol (SIP) and Skinny Client Control Protocol (SCCP) services are
affected by these vulnerabilities.

Cisco has released free software updates for select Cisco Unified
Communications Manager versions 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-20090826-cucm.shtml

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

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

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

  * Cisco Unified Communications Manager 4.x
  * Cisco Unified Communications Manager 5.x
  * Cisco Unified Communications Manager 6.x
  * Cisco Unified Communications Manager 7.x

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

Cisco Unified Communications Manager Express 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.

Malformed SIP Message Vulnerabilities
+------------------------------------

Cisco Unified Communications Manager contains two DoS vulnerabilities
that involve the processing of SIP packets. Each vulnerability is
triggered by a malformed SIP message that could cause a critical
process to fail, resulting in the disruption of voice services. All
SIP ports (TCP 5060 and 5061, UDP 5060 and 5061) are affected by
these vulnerabilities.

The first SIP DoS vulnerability is documented in Cisco Bug ID
CSCsi46466 and has been assigned the CVE identifier CVE-2009-2050.
The first vulnerability is fixed in Cisco Unified Communications
Manager versions 6.1(1) and later.

Cisco Unified Communications Manager 4.x versions are only affected
by the first SIP DoS vulnerability if a SIP trunk is explicitly
configured. To determine if a SIP truck is configured on a Cisco
Unified Communications Manager version 4.x system, navigate to
Device > Trunk and choose the option SIP Trunk in the Cisco Unified
Communications Manager administration interface. To mitigate against
this vulnerability, administrators are advised to restrict access to
TCP and UDP port 5060 on vulnerable Cisco Unified Communications
Manager 4.x systems that are configured to use SIP trunks with
screening devices to valid SIP trunk end points.

The second SIP DoS vulnerability is documented in Cisco Bug ID
CSCsz40392 and has been assigned the CVE identifier CVE-2009-2051.
The second vulnerability is fixed in Cisco Unified Communications
Manager versions 5.1(3g), 6.1(4), and 7.1(2).

Network Connection Tracking Vulnerability
+----------------------------------------

Cisco Unified Communications Manager contains a DoS vulnerability
that involves the tracking of network connections by the embedded
operating system firewall. By establishing many TCP connections with
a vulnerable system, an attacker could overwhelm the operating system
table that is used to track network connections and prevent new
connections from being established to system services. Any service
that listens to a TCP port on a vulnerable system could be affected
by this vulnerability, including SIP and SCCP.

This vulnerability is documented in Cisco Bug ID CSCsq22534 and has
been assigned the CVE identifier CVE-2009-2052. The vulnerability is
fixed in Cisco Unified Communications Manager versions 5.1(3g),
6.1(4), 7.0(2), and 7.1(2).

Related SIP and SCCP DoS Vulnerabilities
+---------------------------------------

Cisco Unified Communications Manager contains two DoS vulnerabilities
involving the processing of SIP and SCCP packets. By flooding a
vulnerable system with many TCP packets, an attacker could exhaust
operating system file descriptors that cause the SIP port (TCP 5060
and 5061) and SCCP port (TCP 2000 and 2443) to close. This action
could prevent new connections from being established to the SIP and
SCCP services. SIP UDP (5060 and 5061) ports are not affected.

The SCCP vulnerability is documented in Cisco Bug ID CSCsx32236 and
has been assigned the CVE identifier CVE-2009-2053. The SCCP
vulnerability is fixed in Cisco Unified Communications Manager
versions 5.1(3g), 6.1(4), 7.0(2a)su1, and 7.1(2).

The SIP vulnerability is documented in Cisco Bug ID CSCsx23689 and
has been assigned the CVE identifier CVE-2009-2054. The SIP
vulnerability is fixed in Cisco Unified Communications Manager
versions 5.1(3g), 6.1(4), 7.0(2a)su1, and 7.1(2a)su1.

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

CSCsi46466 - CM 6.1 SDL router services dead when receiving abnormal

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

CSCsz40392 - CCM: Coredump in sipSafeStrlen from malicious INVITE

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

CSCsq22534 - IP_Conntrack Fills Up During TCP Flood Attack

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

CSCsx32236 - SCCP Port Closed in Response to FD Resource Exhaustion

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

CSCsx23689 - SIP Port Closed in Response to FD Resource Exhaustion

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 could result in the interruption of voice services. To
restore voice services, affected Cisco Unified Communications Manager
services may require a manual restart.

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  |                     |
| Communications  | Recommended Release |
| Manager Version |                     |
|-----------------+---------------------|
|                 | 5.1(3g) (Available  |
| 5.x             | for download in     |
|                 | early September     |
|                 | 2009)               |
|-----------------+---------------------|
| 6.x             | 6.1(4)              |
|-----------------+---------------------|
| 7.x             | 7.1(2a)SU1          |
+---------------------------------------+

Cisco Unified Communications Manager software version 5.1(3g) will be
available for download in early September 2009 at the following link:

http://tools.cisco.com/support/downloads/go/ReleaseType.x?optPlat=null&isPlatform=Y&mdfid=280735907&sftType=Unified%20Communications%20Manager%20Updates&treeName=Voice%20and%20Unified%20Communications&modelName=Cisco%20Unified%20Communications%20Manager%20Version%205.1&mdfLevel=Software%20Version/Option&treeMdfId=278875240&modifmdfid=null&imname=null&hybrid=Y&imst=N

Cisco Unified Communications Manager software version 6.1(4) can be
downloaded at the following link:

http://tools.cisco.com/support/downloads/go/PlatformList.x?sftType=Unified%20Communications%20Manager%20Updates&mdfid=281023410&treeName=Voice%20and%20Unified%20Communications&mdfLevel=Software%20Version/Option&url=null&modelName=Cisco%20Unified%20Communications%20Manager%20Version%206.1&isPlatform=N&treeMdfId=278875240&modifmdfid=null&imname=null&hybrid=Y&imst=N

Administrators are advised to upgrade Cisco Unified Communications
Manager systems running software version 7.0 to version 7.1(2a)SU1.
Cisco Unified Communications Manager software version 7.1(2a)SU1 can
be downloaded at the following link:

http://tools.cisco.com/support/downloads/go/PlatformList.x?sftType=Unified+Communications+Manager+Updates&mdfid=282421166&treeName=Voice+and+Unified+Communications&mdfLevel=Software%20Version/Option&url=null&modelName=Cisco+Unified+Communications+Manager+Version+7.1&isPlatform=N&treeMdfId=278875240&modifmdfid=null&imname=&hybrid=Y&imst=N

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

There are no workarounds for the vulnerabilities in this advisory.
Administrators can mitigate the SCCP- and SIP-related vulnerabilities
by implementing filtering on screening devices to permit access to
TCP ports 2000 and 2443, and TCP and UDP ports 5060 and 5061 only
from networks that need SCCP and SIP access to Cisco Unified
Communications Manager servers.

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-20090826-cucm.shtml

Obtaining Fixed Software
========================

Cisco has released free software updates for select Cisco Unified
Communications Manager versions 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.

Cisco Unified Communications Manager Versions 6.x and Later
+----------------------------------------------------------

Cisco has released free software updates for all vulnerabilities
described in this advisory in Cisco Unified Communications Manager
versions 6.x and 7.x.

Cisco Unified Communications Manager Versions 4.x and 5.x
+--------------------------------------------------------

For Cisco Bug ID Cscsi46466, Cisco will not provide a software fix
for Cisco Unified Communications Manager versions 4.x and 5.x.
Customers who are concerned about the availability of fixed software
for this vulnerability in these releases should contact the following
email address:

cucm-august26-inquiry at cisco.com

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. The
vulnerabilities were discovered 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-20090826-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      | 2009-August-26 | 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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