CVE-2007-5640 in Business Communications Manager
Summary
by MITRE
The Nortel UNIStim IP Softphone 2050, IP Phone 1140E, and additional Nortel products from the IP Phone, Business Communications Manager (BCM), Mobile Voice Client, and other product lines, allow remote attackers to block calls and force re-registration via a resume message to the Signaling Server that has a spoofed source IP address for the phone. NOTE: the attack is more disruptive if a new spoofed resume message is sent after each re-registration.
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Analysis
by VulDB Data Team • 11/03/2017
The vulnerability described in CVE-2007-5640 represents a significant security flaw in Nortel's unified communications infrastructure affecting multiple product lines including the UNIStim IP Softphone 2050, IP Phone 1140E, and various BCM and Mobile Voice Client implementations. This weakness stems from insufficient authentication mechanisms within the signaling protocol implementation, specifically within the registration and call control processes. The vulnerability operates at the network layer where the system fails to validate the authenticity of source IP addresses in signaling messages, creating an avenue for malicious actors to manipulate the communication infrastructure.
The technical exploitation of this vulnerability involves crafting and transmitting spoofed resume messages to the Signaling Server with falsified source IP addresses that appear to originate from legitimate phone devices. This spoofing technique allows attackers to manipulate the registration state of phones within the network, effectively forcing them to re-register with the server. The attack mechanism leverages the trust relationship that exists between the signaling server and registered phones, where legitimate phones are expected to maintain their registration state without external interference. When a spoofed resume message is received, the server processes it as if it came from an authentic device, triggering the re-registration process and disrupting normal communication flows.
The operational impact of this vulnerability extends beyond simple call disruption to encompass broader network stability and security concerns. Remote attackers can systematically force repeated re-registrations, creating a denial of service condition that prevents legitimate users from making or receiving calls. This attack pattern becomes exponentially more disruptive when combined with the ability to send new spoofed resume messages after each re-registration, creating a continuous loop that can effectively render the affected phone systems unusable. The vulnerability affects not just individual phone devices but the entire signaling infrastructure, potentially compromising the integrity of the communication network and creating opportunities for further attacks.
This vulnerability maps to CWE-287 which addresses improper authentication issues in network protocols, specifically targeting the lack of proper source address validation and authentication mechanisms. From an ATT&CK framework perspective, this represents a privilege escalation and denial of service technique that can be classified under T1499.004 for network denial of service and T1566.001 for credential theft through social engineering. The attack vector demonstrates a classic man-in-the-middle approach where an attacker positions themselves to intercept and manipulate signaling traffic without requiring direct access to the network infrastructure. Organizations implementing Nortel's unified communications solutions should consider this vulnerability as part of their broader security posture assessment, particularly in environments where voice communication integrity and availability are critical business functions.
Mitigation strategies for this vulnerability should focus on implementing network-level protections including ingress filtering to validate source IP addresses, deploying intrusion detection systems to monitor for suspicious resume message patterns, and configuring the signaling servers with more robust authentication mechanisms. Network administrators should also consider implementing rate limiting on registration requests and establishing monitoring protocols to detect unusual re-registration patterns that could indicate an active attack. The most effective long-term solution involves upgrading to versions of the software that properly validate source addresses and implement stronger authentication mechanisms for all signaling messages, ensuring that only legitimate devices can influence the registration state of phones within the network infrastructure.