Cisco Security Advisory
Cisco Unified Communications Manager Denial of Service Vulnerabilities
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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 (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 https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20090826-cucm.
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Vulnerable Products
The following products are affected by vulnerabilities described in this advisory:
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Cisco Unified Communications Manager 4.x
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Cisco Unified Communications Manager 5.x
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Cisco Unified Communications Manager 6.x
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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.
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Cisco Unified Communications Manager 4.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.
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.
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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:
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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 Communications Manager Version
Recommended Release
5.x
5.1(3g) (Available 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:
Cisco Unified Communications Manager software version 6.1(4) can be downloaded at the following link:
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:
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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.
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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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Revision 1.0
2009-August-26
Initial public release.
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