CVE-2002-1189 in Unity Server
Summary
by MITRE
The default configuration of Cisco Unity 2.x and 3.x does not block international operator calls in the predefined restriction tables, which could allow authenticated users to place international calls using call forwarding.
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Analysis
by VulDB Data Team • 06/17/2019
The vulnerability identified as CVE-2002-1189 represents a critical security flaw in Cisco Unity messaging systems version 2.x and 3.x that stems from inadequate configuration of call restriction policies. This issue specifically affects the default installation settings where international operator calls are not properly blocked within the predefined restriction tables, creating an unintended access vector for authenticated users to bypass normal call restrictions. The vulnerability exists at the application level within the telephony integration framework of Cisco Unity, which serves as a unified messaging platform combining voicemail, fax, and telephony services. This flaw demonstrates poor security by design principles where default configurations fail to implement proper access controls for international calling capabilities.
The technical implementation of this vulnerability occurs through the call forwarding mechanism within Cisco Unity's telephony subsystem, where authenticated users can leverage their privileges to route calls through international operator connections despite system restrictions. The flaw resides in the restriction table configuration that governs outbound call routing, specifically failing to properly filter international operator numbers in the default security policies. When users authenticate to the system, they gain access to call forwarding features that should be restricted to prevent unauthorized international calling. The vulnerability exploits the gap between the expected security boundaries and the actual implementation of call restriction enforcement, allowing malicious or unauthorized users to make international calls without proper authorization. This issue is classified under CWE-693 which deals with Protection Mechanism Failure, specifically in the context of improper restriction of communications between systems.
Operationally, this vulnerability presents significant risks to organizations using Cisco Unity systems, as it enables authenticated users to make unauthorized international calls that could result in substantial financial losses through premium rate services and international roaming charges. The impact extends beyond simple monetary loss to include potential security breaches where unauthorized international communication channels could be exploited for data exfiltration or command and control activities. Attackers could potentially use this vulnerability to establish covert communication channels or to make calls to premium rate numbers that would be difficult to trace back to the compromised system. The vulnerability affects the integrity and availability of the communication system, as it allows unauthorized users to consume system resources and potentially disrupt legitimate call routing operations. Organizations may face regulatory compliance issues and increased costs related to unauthorized international calling charges.
Organizations should implement immediate mitigations including manual configuration of restriction tables to explicitly block international operator numbers, regular security audits of call restriction policies, and implementation of monitoring systems to detect unauthorized international calling patterns. The recommended approach involves updating the default restriction tables to include comprehensive blocking of international operator prefixes and implementing additional authentication controls for call forwarding features. Network administrators should also consider implementing call logging and alerting mechanisms to detect suspicious international calling activities. According to ATT&CK framework, this vulnerability relates to T1078 Valid Accounts and T1566 Phishing techniques, as it leverages legitimate authenticated access to perform unauthorized actions. Organizations should also review their security configurations against NIST SP 800-53 control families, particularly those related to system and information integrity controls, to ensure proper implementation of access control mechanisms and audit logging capabilities. The vulnerability underscores the importance of proper security configuration management and regular security assessments to prevent exploitation of default security settings in enterprise communication systems.