CVE-2008-4543 in Unity
Summary
by MITRE
Cisco Unity 4.x before 4.2(1)ES161, 5.x before 5.0(1)ES53, and 7.x before 7.0(2)ES8, when using anonymous authentication (aka native Unity authentication), allows remote attackers to cause a denial of service (session exhaustion) via a large number of connections.
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Analysis
by VulDB Data Team • 08/19/2019
Cisco Unity is a unified communications platform that provides voicemail, messaging, and telephony integration services for enterprise environments. The vulnerability exists in versions 4.x before 4.2(1)ES161, 5.x before 5.0(1)ES53, and 7.x before 7.0(2)ES8 of the Cisco Unity software when configured to use anonymous authentication or native Unity authentication mechanisms. This authentication method allows users to access the system without requiring traditional username and password credentials, which can be useful for certain operational scenarios but introduces significant security risks when not properly constrained.
The technical flaw stems from insufficient connection management and resource allocation controls within the Unity authentication subsystem. When anonymous authentication is enabled, the system does not adequately limit or monitor the number of concurrent connections that can be established by remote attackers. This creates a session exhaustion vulnerability where malicious actors can establish a large number of simultaneous connections to the system, consuming available session resources and preventing legitimate users from accessing the service. The vulnerability specifically affects the handling of authentication requests and connection establishment processes, where the system fails to implement proper rate limiting or connection throttling mechanisms.
The operational impact of this vulnerability is significant as it enables remote attackers to perform denial of service attacks against Cisco Unity systems without requiring any authentication credentials. Attackers can exploit this weakness to consume all available system resources, effectively rendering the unified communications service unavailable to legitimate users. This can result in business disruption, communication failures, and potential financial losses for organizations relying on the affected Cisco Unity platforms. The vulnerability is particularly dangerous because it does not require any specialized credentials or privileges to exploit, making it accessible to anyone who can reach the system over the network.
This vulnerability aligns with CWE-400, which describes "Uncontrolled Resource Consumption" or "Resource Exhaustion" in software systems. The flaw demonstrates poor resource management practices where the system does not implement adequate safeguards against excessive connection attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving resource exhaustion and denial of service attacks, specifically targeting the availability aspect of the CIA triad. Organizations should implement network-level controls such as connection rate limiting, firewall rules, and intrusion detection systems to monitor for unusual connection patterns. The recommended mitigation includes upgrading to patched versions of Cisco Unity software, implementing proper authentication controls, and configuring connection limits to prevent excessive resource consumption. Additionally, network segmentation and monitoring solutions should be deployed to detect and respond to potential exploitation attempts.