CVE-2007-5591 in VoIP-Core-CS
Summary
by MITRE
The CS1000 signaling server in Nortel Enterprise VoIP-Core-CS 1000M Chassis/Cabinet, Enterprise VoIP-Core-CS 1000E and 1000S, Meridian-Core-Option 11C Chassis and Cabinet, and Meridian-Core-Option 51C, 61C, and 81C allows remote attackers to cause a denial of service (telephony application outage) via a flood of packets to Embedded LAN (ELAN) ports.
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Analysis
by VulDB Data Team • 09/10/2018
The vulnerability described in CVE-2007-5591 represents a critical denial of service weakness affecting Nortel's enterprise voice over internet protocol infrastructure products. This flaw specifically targets the CS1000 signaling server implementations across multiple chassis and cabinet configurations including the VoIP-Core-CS 1000M, E, and S models alongside various Meridian-Core-Option configurations. The vulnerability manifests through a sophisticated packet flooding attack that specifically targets Embedded LAN (ELAN) ports within these telephony systems, creating a cascading failure that can bring entire telephony applications to a complete halt.
The technical mechanism behind this vulnerability involves the exploitation of insufficient input validation and packet processing controls within the signaling server's network stack. When remote attackers flood ELAN ports with excessive packet traffic, the system's ability to process legitimate signaling messages becomes overwhelmed, leading to resource exhaustion and subsequent application failure. This particular weakness demonstrates a fundamental flaw in the system's traffic handling capabilities, where the signaling server lacks adequate rate limiting or traffic shaping mechanisms to distinguish between legitimate operational traffic and malicious flooding attempts. The vulnerability operates at the network protocol level, specifically targeting the embedded local area network interfaces that handle critical telephony signaling communications.
The operational impact of this vulnerability extends far beyond simple service disruption, as it represents a significant threat to enterprise communication infrastructure reliability and business continuity. When exploited, the denial of service condition can result in complete telephony application outages across affected networks, potentially affecting thousands of users within enterprise environments. The attack vector's remote nature means that adversaries can initiate the disruption from anywhere on the network, eliminating the need for physical access or insider knowledge. This vulnerability particularly affects organizations relying on Nortel's legacy telephony infrastructure, where the signaling server acts as a critical component in managing call setup, routing, and termination processes, making it a prime target for attackers seeking to disrupt business operations.
Mitigation strategies for this vulnerability require a multi-layered approach focusing on network segmentation, traffic monitoring, and system hardening. Organizations should implement network access control lists to restrict access to ELAN ports from unauthorized sources and deploy intrusion detection systems capable of identifying abnormal packet flooding patterns. The implementation of rate limiting mechanisms at network boundaries and within the signaling server itself can help prevent the overwhelming traffic conditions that trigger the denial of service. Additionally, regular firmware updates and security patches from Nortel should be applied to address the underlying protocol processing flaws, though this may be challenging given the age of affected systems. According to CWE standards, this vulnerability maps to CWE-400, representing an unchecked resource consumption issue, while ATT&CK framework categorizes this under T1499.004 for network denial of service attacks targeting enterprise communication systems. Organizations should also consider implementing redundant communication paths and backup telephony systems to maintain operational continuity during potential exploitation events.