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Cisco Security Advisory: Multiple Cisco Unified CallManager and
Presence Server Denial of Service Vulnerabilities
Advisory ID: cisco-sa-20070328-voip
http://www.cisco.com/warp/public/707/cisco-sa-20070328-voip.shtml
Revision 1.0
For Public Release 2007 March 28 1600 UTC (GMT)
- ---------------------------------------------------------------------
Summary
=======
Cisco Unified CallManager (CUCM) and Cisco Unified Presence Server
(CUPS) contain multiple vulnerabilities which may result in the
failure of CUCM or CUPS functionality, resulting in a Denial of
Service (DoS) condition. There are no workarounds for these
vulnerabilities. Cisco has made free software available to address
these vulnerabilities for affected customers.
This advisory is posted at
http://www.cisco.com/warp/public/707/cisco-sa-20070328-voip.shtml
Affected Products
=================
Vulnerable Products
+------------------
* Cisco Unified CallManager 3.3 versions prior to 3.3(5)SR2a
* Cisco Unified CallManager 4.1 versions prior to 4.1(3)SR4
* Cisco Unified CallManager 4.2 versions prior to 4.2(3)SR1
* Cisco Unified CallManager 5.0 versions prior to 5.0(4a)SU1
* Cisco Unified Presence Server 1.0 versions prior to 1.0(3)
The software version of a CUCM / CUPS system can be determined by
navigating to Show > Software via the administration interface.
For CUCM version 5.0 and CUPS version 1.0 systems, the software
version can also be determined by running the command show version
active in the Command Line Interface (CLI).
For CUCM version 3.x and 4.x systems, the software version can be
determined by navigating to Help > About Cisco Unified CallManager
and selecting the Details button via the administration interface.
Products Confirmed Not Vulnerable
+--------------------------------
CUCM versions 4.3(1) and 5.1(1) are not affected by any of the
vulnerabilities described in this advisory. No other Cisco products
are currently known to be affected by these vulnerabilities.
Details
=======
Cisco Unified CallManager (CUCM) is the call processing component of
the Cisco IP telephony solution which extends enterprise telephony
features and functions to packet telephony network devices such as IP
phones, media processing devices, voice-over-IP (VoIP) gateways, and
multimedia applications.
Cisco Unified Presence Server (CUPS) is the identity tracking
component of the Cisco IP telephony solution which collects
information about a user's availability status, such as whether or
not you are using a communications device such as a phone at a
particular time. It also collects information regarding a user's
communications capabilities, such as whether Web collaboration or
video conferencing is enabled.
* SCCP/SCCPS Port Scan Denial of Service
Skinny Call Control Protocol (SCCP) is a Cisco proprietary voice
protocol used to facilitate call management functions between
CallManager systems and IP phones. SCCP uses TCP port 2000 for
communications. Secure SCCP (SCCPS) running on TCP port 2443 is also
affected. By sending a series of specially-crafted packets to the
SCCP service port, it may be possible to crash a CallManager system
resulting in a denial of service affecting voice services. CUCM
versions 3.x, 4.x and 5.0 are affected by this vulnerability. CUPS is
not affected by this vulnerability. This issue is documented in Cisco
Bug ID CSCsf10805.
* ICMP Echo Request Flood Denial of Service
By sending a large amount of ICMP Echo Requests (Ping) to a CUCM or
CUPS system, it may be possible to cause various CUCM / CUPS services
to crash resulting in a denial of service affecting voice services.
CUCM versions 3.x and 4.x are not affected by this vulnerability,
only CUCM version 5.0 is affected. The CUCM issue is documented in
Cisco Bug ID CSCsf12698. The CUPS issue is documented in Cisco Bug ID
CSCsg60930.
* IPSec Manager Denial of Service
The IPSec Manager Service of CUCM and CUPS is responsible for
maintaining the connections between CUCM / CUPS systems deployed as a
cluster. By sending a specific UDP packet to the IPSec Manager
Service on UDP port 8500, it may be possible to cause the service to
fail. This would impact advanced call features such as call
forwarding and the ability to deploy configuration changes to CUCM /
CUPS systems in a cluster. Standard call operations including the
ability to place and receive calls will continue to function.
Established calls will not be affected. CUCM versions 3.x and 4.x are
not affected by this vulnerability, only CUCM version 5.0 is
affected. The CUCM issue is documented in Cisco Bug ID CSCsg20143.
The CUPS issue is documented in Cisco Bug ID CSCsg60949.
Vulnerability Scoring Details
=============================
Cisco is providing scores for the vulnerabilities in this advisory
based on the Common Vulnerability Scoring System (CVSS).
Cisco will provide a base and temporal score. Customers can then
compute environmental scores to assist in determining the impact of
the vulnerability in individual networks.
Cisco PSIRT will set the bias in all cases to normal. Customers are
encouraged to apply the bias parameter when determining the
environmental impact of a particular vulnerability.
CVSS is a standards based scoring method that conveys vulnerability
severity and helps determine urgency and priority of response.
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
CSCsf10805 - Cisco Unified CallManager SCCP Port Scan Denial of Service
+----------------------------------------------------------------------
CVSS Base Score: 3.3
Access Vector: Remote
Access Complexity: Low
Authentication: Not Required
Confidentiality Impact: None
Integrity Impact: None
Availability Impact: Complete
Impact Bias: Normal
CVSS Temporal Score: 2.7
Exploitability: Functional
Remediation Level: Official Fix
Report Confidence: Confirmed
CSCsf12698 - Cisco Unified CallManager ICMP Denial of Service
+------------------------------------------------------------
CVSS Base Score: 3.3
Access Vector: Remote
Access Complexity: Low
Authentication: Not Required
Confidentiality Impact: None
Integrity Impact: None
Availability Impact: Complete
Impact Bias: Normal
CVSS Temporal Score: 2.7
Exploitability: Functional
Remediation Level: Official Fix
Report Confidence: Confirmed
CSCsg60930 - Cisco Unified Presence Server ICMP Denial of Service
+----------------------------------------------------------------
CVSS Base Score: 3.3
Access Vector: Remote
Access Complexity: Low
Authentication: Not Required
Confidentiality Impact: None
Integrity Impact: None
Availability Impact: Complete
Impact Bias: Normal
CVSS Temporal Score: 2.7
Exploitability: Functional
Remediation Level: Official Fix
Report Confidence: Confirmed
CSCsg20143 - Cisco Unified CallManager IPSec_Mgr UDP Probe Denial of Service
+---------------------------------------------------------------------------
CVSS Base Score: 4.7
Access Vector: Remote
Access Complexity: Low
Authentication: Not Required
Confidentiality Impact: None
Integrity Impact: Partial
Availability Impact: Partial
Impact Bias: Normal
CVSS Temporal Score: 3.9
Exploitability: Functional
Remediation Level: Official Fix
Report Confidence: Confirmed
CSCsg60949 - Cisco Unified Presence Server IPSec_Mgr UDP Probe Denial of Service
+-------------------------------------------------------------------------------
CVSS Base Score: 4.7
Access Vector: Remote
Access Complexity: Low
Authentication: Not Required
Confidentiality Impact: None
Integrity Impact: Partial
Availability Impact: Partial
Impact Bias: Normal
CVSS Temporal Score: 3.9
Exploitability: Functional
Remediation Level: Official Fix
Report Confidence: Confirmed
Impact
======
* SCCP/SCCPS Port Scan Denial of Service
Successful exploitation of this vulnerability may result in the
failure of CUCM causing a disruption of voice services.
* ICMP Echo Request Flood Denial of Service
Successful exploitation of this vulnerability may result in the
failure of CUCM / CUPS causing a disruption of voice services.
* IPSec Manager Denial of Service
Successful exploitation of this vulnerability may result in the
failure of certain CUCM / CUPS cluster operations including the
advanced phone services like call forwarding and the ability
propagate configuration changes between cluster nodes. Standard voice
services will continue to function normally.
Software Version 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.
Fixed software for CUCM and CUPS can be obtained here:
CUCM 3.3 - Fixed in 3.3(5)SR2a, available at
http://www.cisco.com/cgi-bin/tablebuild.pl/callmgr-33?psrtdcat20e2
CUCM 4.1 - Fixed in 4.1(3)SR4, available at
http://www.cisco.com/cgi-bin/tablebuild.pl/callmgr-41?psrtdcat20e2
CUCM 4.2 - Fixed in 4.2(3)SR1, available at
http://www.cisco.com/cgi-bin/tablebuild.pl/callmgr-42?psrtdcat20e2
CUCM 5.0 - Fixed in 5.0(4a)SU1, available at
http://www.cisco.com/cgi-bin/tablebuild.pl/callmgr-50?psrtdcat20e2
CUPS 1.0 - Fixed in 1.0(3), available at
http://www.cisco.com/cgi-bin/tablebuild.pl/cups-10?psrtdcat20e2
Workarounds
===========
There are no workarounds for these vulnerabilities.
Filtering traffic as follows for affected CUCM / CUPS systems can be
used as a mitigation technique:
* Permit TCP port 2000 (SCCP) and TCP port 2443 (SCCPS) to CUCM
systems only from VoIP endpoints.
* ICMP Echo Requests (type 8) should be blocked for CUCM and CUPS
systems. This may affect network management applications and
troubleshooting procedures.
* UDP Port 8500 (IPSec Manager) should only be permitted between
CUCM / CUPS systems configured in a cluster deployment.
The ICMP Echo Request Flood Denial of Service and IPSec Manager
Denial of Service vulnerabilities, described in this document may be
exploited by spoofed attacks.
Transit Access Lists can also be deployed at your network edge as a
potential mitigation technique. Refer to
http://www.cisco.com/warp/public/707/tacl.html for examples on how to
apply ACLs on Cisco routers and switches for protection.
Additional mitigations that can be deployed on Cisco devices within
the network are available in the Cisco Applied Intelligence companion
document for this advisory:
http://www.cisco.com/warp/public/707/cisco-air-20070328-voip.shtml
Obtaining Fixed Software
========================
Cisco will make free software available to address this vulnerability
for affected customers. This advisory will be updated as fixed
software becomes available. 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/public/sw-license-agreement.html, or as
otherwise set forth at Cisco.com Downloads at
http://www.cisco.com/public/sw-center/sw-usingswc.shtml.
Do not contact either "psirt@private" or "security-alert@private"
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 agreement 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 who do not hold a Cisco
service contract and customers who purchase through third-party
vendors but are unsuccessful at obtaining fixed software through
their point of sale should get their 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@private
Have your product serial number available and give the URL of this
notice as evidence of your 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 special 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.
The SCCP denial of service vulnerability was reported to Cisco by a
customer. The ICMP Echo Request and IPSec Manager Service denial of
service vulnerabilities were discovered internally 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-20070328-voip.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@private
* first-teams@private
* bugtraq@private
* vulnwatch@private
* cisco@private
* cisco-nsp@private
* full-disclosure@private
* comp.dcom.sys.cisco@private
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 | 2007-March-28 | 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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