Cisco IOS Software and Cisco Unified Communications Manager contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.
The vulnerability is due to improper processing of Session Initiation Protocol (SIP) messages that contain a valid Session Description Protocol (SDP) message by the affected software. An unauthenticated, remote attacker could exploit this vulnerability by sending crafted SIP packets to a targeted device. If successful, the attacker could cause the device to reload, resulting in a DoS condition.
Cisco has confirmed this vulnerability and software updates are available.
Indicators of Compromise
Cisco has published a list of affected Cisco IOS Software releases in the security advisory. The Vendor Announcements section of this alert contains a link to the advisory.
The following Cisco Unified Communications Manager versions are affected:
versions 6.1(5) and prior
versions 7.0(2) and prior
versions 7.1(5b) and prior
versions 8.0(3) and prior
The vulnerability is due to improper processing of SIP messages that contain a valid SDP message by the affected software when it is configured to use SIP. SDP pass-through must be enabled for a targeted device to be affected by this vulnerability.
An unauthenticated, remote attacker could exploit this vulnerability by sending malicious SIP packets to a vulnerable device via TCP and UDP port 5060 or TCP Transport Layer Security (TLS) port 5061. When the packets are processed, it could cause the device to reload, resulting in a DoS condition.
To exploit this vulnerability, the attacker must send a crafted SIP message that contains a valid SDP message to a targeted system. To achieve this objective, the attacker may need access to trusted, internal network resources. This access requirement reduces the likelihood of a successful exploit.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only legitimate devices to connect to affected devices.
Administrators are advised to monitor affected systems.
Administrators may consider disabling the SIP process if it is not required. SIP can be disabled by issuing the following commands: sip-uano transport udp, no transport tcp, and no transport tcp tls.
The Cisco Applied Intelligence team has created the following companion document to guide administrators in identifying and mitigating attempts to exploit this vulnerability prior to applying updated software: cisco-amb-20120926-cucm
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at firstname.lastname@example.org.
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Cisco Multivendor Vulnerability Alerts respond to vulnerabilities identified in third-party vendors' products. These alerts contain information compiled from diverse sources and provide comprehensive technical descriptions, objective analytical assessments, workarounds and practical safeguards, and links to vendor advisories and patches.