CVE-2015-4316 in TelePresence Video Communication Server
Summary
by MITRE
The Mobile and Remote Access (MRA) endpoint-validation feature in Cisco TelePresence Video Communication Server (VCS) Expressway X8.5.2 improperly validates the phone line used for registration, which allows remote authenticated users to conduct impersonation attacks via a crafted registration, aka Bug ID CSCuv40396.
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Analysis
by VulDB Data Team • 06/12/2022
The vulnerability identified as CVE-2015-4316 resides within the Mobile and Remote Access endpoint-validation functionality of Cisco TelePresence Video Communication Server (VCS) Expressway version 8.5.2. This flaw represents a critical security weakness in the system's authentication and authorization mechanisms, specifically targeting the validation process for phone line registration. The issue enables malicious actors who already possess legitimate credentials to exploit the system's trust model and impersonate other users or devices within the network infrastructure. The vulnerability's classification as an endpoint validation flaw indicates that the system fails to properly verify the authenticity of registration requests, creating a pathway for unauthorized access and potential network compromise.
The technical implementation of this vulnerability stems from inadequate input validation within the MRA endpoint registration process. When legitimate users attempt to register their endpoints with the VCS Expressway system, the validation mechanism should rigorously verify the phone line information provided during registration. However, the flawed implementation allows attackers to manipulate registration requests by crafting specific phone line parameters that bypass the system's validation checks. This weakness operates at the protocol level where the system accepts user-provided phone line identifiers without sufficient cryptographic verification or database consistency checks, creating an impersonation vector that can be exploited by authenticated users who understand the system's registration flow.
The operational impact of CVE-2015-4316 extends beyond simple unauthorized access, as it fundamentally undermines the trust model of the video communication infrastructure. Successful exploitation allows attackers to register devices or endpoints using falsified phone line information, potentially enabling them to gain access to privileged communication channels, intercept sensitive video conferences, or manipulate access controls for legitimate users. This vulnerability particularly affects organizations relying on Cisco VCS Expressway for secure video collaboration, as it creates opportunities for man-in-the-middle attacks, credential theft, and unauthorized network penetration. The implications are especially severe in enterprise environments where video communication systems serve as critical infrastructure for business operations and sensitive data exchange.
Organizations should implement immediate mitigations including upgrading to Cisco software versions that address this vulnerability, typically those released after the initial patching cycle for CSCuv40396. Network segmentation and enhanced monitoring of registration activities can help detect anomalous endpoint registration patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-284 (Improper Access Control) and CWE-345 (Insufficient Verification of Data Authenticity) categories, reflecting weaknesses in access control validation and data integrity verification. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and credential access, specifically T1078 (Valid Accounts) and T1566 (Phishing). Additional defensive measures should include implementing stricter authentication requirements for endpoint registration, enabling logging and alerting for registration events, and conducting regular security assessments of communication infrastructure to identify similar validation weaknesses in other network components.