Cisco Security Advisory
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AV:R/AC:L/Au:NR/C:N/I:P/A:P/B:N/E:F/RL:O/RC:C
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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 https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20070328-voip.
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Vulnerable Products
These products are vulnerable:
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Cisco Unified CallManager 3.3 versions prior to
3.3(5)SR2a
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Cisco Unified CallManager 4.1 versions prior to
4.1(3)SR4
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Cisco Unified CallManager 4.2 versions prior to
4.2(3)SR1
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Cisco Unified CallManager 5.0 versions prior to
5.0(4a)SU1
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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.
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Cisco Unified CallManager 3.3 versions prior to
3.3(5)SR2a
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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.
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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.
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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.
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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.
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SCCP/SCCPS Port Scan Denial of Service
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There are no workarounds for these vulnerabilities.
Filtering traffic as follows for affected CUCM / CUPS systems can be used as a mitigation technique:
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Permit TCP port 2000 (SCCP) and TCP port 2443 (SCCPS) to CUCM systems
only from VoIP endpoints.
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ICMP Echo Requests (type 8) should be blocked for CUCM and CUPS
systems. This may affect network management applications and troubleshooting
procedures.
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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 Mitigation Bulletin companion document for this advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoAppliedMitigationBulletin/cisco-amb-20070328-voip
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Permit TCP port 2000 (SCCP) and TCP port 2443 (SCCPS) to CUCM systems
only from VoIP endpoints.
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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 Version
Fixed Release
Download Location
CUCM 3.3
CUCM 3.3(5)SR2a
http://www.cisco.com/pcgi-bin/tablebuild.pl/callmgr-33?psrtdcat20e2
CUCM 4.1
CUCM 4.1(3)SR4
http://www.cisco.com/pcgi-bin/tablebuild.pl/callmgr-41?psrtdcat20e2
CUCM 4.2
CUCM 4.2(3)SR1
http://www.cisco.com/pcgi-bin/tablebuild.pl/callmgr-42?psrtdcat20e2
CUCM 5.0
CUCM 5.0(4a)SU1
http://www.cisco.com/pcgi-bin/tablebuild.pl/callmgr-50?psrtdcat20e2
CUPS Version
Fixed Release
Download Location
CUPS 1.0
CUPS 1.0(3)
http://www.cisco.com/pcgi-bin/tablebuild.pl/cups-10?psrtdcat20e2
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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.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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