CVE-2018-0139 in Unified Customer Voice Portal
Summary
by MITRE
A vulnerability in the Interactive Voice Response (IVR) management connection interface for Cisco Unified Customer Voice Portal (CVP) could allow an unauthenticated, remote attacker to cause the IVR connection to disconnect, creating a system-wide denial of service (DoS) condition. The vulnerability is due to improper handling of a TCP connection request when the IVR connection is already established. An attacker could exploit this vulnerability by initiating a crafted connection to the IP address of the targeted CVP device. An exploit could allow the attacker to disconnect the IVR to CVP connection, creating a DoS condition that prevents the CVP from accepting new, incoming calls while the IVR automatically attempts to re-establish the connection to the CVP. This vulnerability affects Cisco Unified Customer Voice Portal (CVP) Software Release 11.5(1). Cisco Bug IDs: CSCve70560.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 02/04/2021
The vulnerability identified as CVE-2018-0139 resides within the Interactive Voice Response management connection interface of Cisco Unified Customer Voice Portal systems, representing a significant security flaw that enables remote attackers to disrupt critical telephony services. This weakness specifically targets the software release 11.5(1) of the Cisco CVP platform, where the system's improper handling of TCP connection requests creates a pathway for malicious exploitation. The vulnerability operates through a fundamental flaw in the connection management protocols that govern how the IVR system interacts with the CVP device, creating a condition where legitimate connection attempts can be disrupted by crafted malicious inputs.
The technical implementation of this vulnerability stems from inadequate state management within the TCP connection handling mechanism of the IVR interface. When an IVR connection is already established with the CVP system, the software fails to properly process subsequent connection requests, leading to connection termination and subsequent system-wide service disruption. This flaw manifests when an unauthenticated attacker sends specially crafted TCP connection packets to the target CVP device's IP address, triggering the improper connection handling behavior that results in disconnection of the IVR to CVP communication channel. The vulnerability demonstrates characteristics consistent with CWE-121, which addresses buffer overflow conditions that can lead to system instability, though in this case the impact is more specifically related to connection state management failures rather than memory corruption.
The operational impact of this vulnerability extends beyond simple service disruption to create a comprehensive denial of service condition that affects the entire customer voice portal infrastructure. When exploited successfully, the vulnerability forces the IVR system to disconnect from the CVP, preventing the system from accepting new incoming calls while the IVR automatically attempts to re-establish the connection. This creates a cascading effect where legitimate customer interactions are blocked until the connection is restored, potentially resulting in significant business disruption for organizations relying on these telephony services. The vulnerability's remote exploitability means that attackers do not require physical access or authentication credentials to cause the disruption, making it particularly dangerous in networked environments where the CVP system may be exposed to external network traffic.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1499.002, which covers network denial of service attacks, and represents a classic example of how improper input validation and connection state management can create exploitable conditions. The vulnerability's characteristics suggest that it could be leveraged as part of broader attack campaigns targeting telecommunications infrastructure, potentially leading to more sophisticated attacks that exploit the resulting system instability. Organizations implementing Cisco CVP solutions should consider this vulnerability as part of their broader security posture assessment, particularly in environments where voice services are critical to business operations. The exploitability of this vulnerability through simple TCP connection manipulation makes it particularly concerning for organizations that have not implemented proper network segmentation or access controls to limit external exposure of their voice portal systems. Remediation efforts should focus on applying the vendor-supplied patch referenced in Cisco Bug ID CSCve70560, while also implementing network-level protections such as access control lists and firewall rules to restrict unnecessary access to the affected CVP management interfaces.