CVE-2015-0616 in Unity Connection
Summary
by MITRE
The Connection Conversation Manager (CuCsMgr) process in Cisco Unity Connection 8.5 before 8.5(1)SU7, 8.6 before 8.6(2a)SU4, and 9.x before 9.1(2)SU2, when SIP trunk integration is enabled, allows remote attackers to cause a denial of service (core dump and restart) by improperly terminating SIP TCP connections, aka Bug ID CSCul69819.
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Analysis
by VulDB Data Team • 05/02/2022
The vulnerability identified as CVE-2015-0616 affects Cisco Unity Connection systems running specific versions where the Connection Conversation Manager process fails to properly handle termination of SIP TCP connections. This flaw exists within the SIP trunk integration functionality and represents a critical denial of service weakness that can be exploited remotely by attackers without authentication requirements. The vulnerability specifically impacts systems configured with SIP trunk integration enabled, making it particularly concerning for organizations relying on unified communications infrastructure. The issue manifests when improperly terminated SIP TCP connections trigger core dump generation and subsequent system restarts, effectively disrupting communication services.
The technical root cause of this vulnerability lies in the improper handling of TCP connection termination within the CuCsMgr process of Cisco Unity Connection. When SIP trunk integration is enabled, the system does not adequately validate or manage the termination sequence of TCP connections, leading to memory corruption or process instability. This weakness falls under the category of improper handling of resources, specifically related to connection management and resource cleanup. The flaw can be categorized as a CWE-400 vulnerability, representing an unchecked resource consumption issue where the system fails to properly manage TCP connection lifecycle events. The improper termination sequence causes the process to crash and restart, creating a denial of service condition that can be repeatedly triggered by an attacker.
The operational impact of this vulnerability extends beyond simple service disruption as it can lead to complete communication outages within affected organizations. The system restarts caused by the core dumps can result in loss of active calls, disruption of voice messaging services, and potential data loss from unsaved communications. Organizations relying on Cisco Unity Connection for business-critical communications may experience significant downtime, affecting productivity and customer service availability. The vulnerability's remote exploitability means attackers can target systems from outside the network perimeter, making it particularly dangerous for organizations with exposed SIP trunks. This type of vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks that can be executed through manipulation of network protocols and connection management.
Mitigation strategies for CVE-2015-0616 require immediate implementation of official Cisco security patches and updates to affected systems. Organizations should upgrade to the patched versions specified in Cisco security advisories, particularly versions 8.5(1)SU7, 8.6(2a)SU4, and 9.1(2)SU2. Network segmentation and firewall rules should be implemented to restrict access to SIP trunk endpoints, limiting exposure to unauthorized connection termination attempts. Monitoring systems should be configured to detect unusual connection termination patterns that could indicate exploitation attempts. Additionally, implementing connection rate limiting and proper TCP connection timeout configurations can help reduce the impact of potential attacks. The vulnerability demonstrates the importance of proper resource management in telecommunications systems and highlights the need for robust error handling in protocol implementations. Organizations should also consider implementing intrusion detection systems that can identify and alert on suspicious SIP connection termination patterns, providing early warning of potential exploitation attempts.