Cisco Security Advisory
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AV:N/AC:L/Au:N/C:N/I:N/A:C/E:F/RL:OF/RC:C
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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 https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20100825-cucm.
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Vulnerable Products
The following products are affected by vulnerabilities that are described in this advisory:
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Cisco Unified Communications Manager 6.x
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Cisco Unified Communications Manager 7.x
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Cisco Unified Communications Manager
8.x
Products Confirmed Not Vulnerable
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.
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Cisco Unified Communications Manager 6.x
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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.
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There are no workarounds for the vulnerabilities described in this advisory.
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:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/admin/7_0_1/ccmcfg/b02ccm.html#wp1057513
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:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucmbe/admin/7_0_1/ccmcfg/b03dpi.html#wp1075124
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:
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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.
Cisco Unified Communication Manager Version
Recommended Release
6.x
6.1(5)SU1
7.x
7.1(5b)SU2
8.x
8.0(3a)
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 following link:
https://sec.cloudapps.cisco.com/support/downloads/go/Redirect.x?mdfid=268439621
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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.
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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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