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Multiple Cisco Unified CallManager and Presence Server DoS Vulnerabilities
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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.
DETAILS
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.
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.
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>
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>
http://www.cisco.com/warp/public/707/cisco-air-20070328-voip.shtml
ADDITIONAL INFORMATION
The information has been provided by <mailto:psirt@cisco.com> Cisco
Systems Product Security Incident Response Team.
The original article can be found at:
<http://www.cisco.com/warp/public/707/cisco-sa-20070328-voip.shtml>
http://www.cisco.com/warp/public/707/cisco-sa-20070328-voip.shtml
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