CVE-2018-0086 in Unified Customer Voice Portal
Summary
by MITRE
A vulnerability in the application server of the Cisco Unified Customer Voice Portal (CVP) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on the affected device. The vulnerability is due to malformed SIP INVITE traffic received on the CVP during communications with the Cisco Virtualized Voice Browser (VVB). An attacker could exploit this vulnerability by sending malformed SIP INVITE traffic to the targeted appliance. An exploit could allow the attacker to impact the availability of services and data on the device, causing a DoS condition. This vulnerability affects Cisco Unified CVP running any software release prior to 11.6(1). Cisco Bug IDs: CSCve85840.
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Analysis
by VulDB Data Team • 02/01/2021
The vulnerability described in CVE-2018-0086 represents a critical denial of service weakness within Cisco's Unified Customer Voice Portal application server ecosystem. This flaw specifically targets the processing of Session Initiation Protocol INVITE messages, which are fundamental to voice communication in telephony systems. The vulnerability exists in the interaction between Cisco Unified CVP and Cisco Virtualized Voice Browser components, creating a pathway for remote exploitation without requiring authentication credentials. The affected system operates under Cisco software releases prior to version 11.6(1), indicating that organizations running older versions remain at significant risk of service disruption.
The technical mechanism behind this vulnerability involves the improper handling of malformed SIP INVITE traffic that arrives at the CVP appliance during communication sessions with the VVB. When the system receives these specially crafted malicious packets, the application server fails to properly parse or validate the SIP message structure, leading to unexpected behavior and system instability. This processing failure manifests as a complete service disruption, effectively rendering the targeted appliance unable to process legitimate voice communication requests. The vulnerability operates at the protocol level within the SIP communication stack, making it particularly dangerous as it can be triggered through standard network traffic without requiring privileged access or complex exploitation techniques.
From an operational perspective, this vulnerability presents a severe threat to voice communication infrastructure reliability and business continuity. Organizations relying on Cisco Unified CVP for customer service operations face potential disruptions that could impact customer support availability, call handling capabilities, and overall service quality metrics. The remote nature of the attack means that adversaries can exploit this weakness from anywhere on the network, potentially causing widespread service degradation across multiple communication channels. The DoS condition affects not just individual phone lines but can potentially compromise entire voice portal systems, leading to cascading failures in customer service operations and possible financial losses due to service unavailability.
Security professionals should recognize this vulnerability as aligning with CWE-20, which describes "Improper Input Validation" in software systems, and specifically relates to CWE-129, "Improper Validation of Array Index." The attack pattern corresponds to techniques documented in the MITRE ATT&CK framework under the T1499.004 sub-technique for "Endpoint Denial of Service" and T1071.004 for "Application Layer Protocol: SIP." Organizations should implement immediate mitigation strategies including applying the relevant Cisco security patches and updates, implementing network segmentation to limit exposure, and deploying intrusion detection systems to monitor for suspicious SIP traffic patterns. The vulnerability underscores the importance of maintaining up-to-date security controls and demonstrates how seemingly minor protocol processing flaws can result in significant operational impacts within critical communication infrastructure.