CVE-2015-6413 in TelePresence Video Communication Server Expressway
Summary
by MITRE
Cisco TelePresence Video Communication Server (VCS) Expressway X8.6 allows remote authenticated users to bypass intended read-only restrictions and upload Tandberg Linux Package (TLP) files by visiting an administrative page, aka Bug ID CSCuw55651.
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Analysis
by VulDB Data Team • 06/30/2022
The vulnerability identified as CVE-2015-6413 affects Cisco TelePresence Video Communication Server (VCS) Expressway running software version 8.6 and potentially other versions. This represents a critical authorization bypass flaw that undermines the security model of the system by allowing authenticated users to escalate their privileges and perform actions beyond their intended permissions. The vulnerability specifically targets the administrative interface of the VCS Expressway, where legitimate users with read-only access can exploit a design flaw to gain upload capabilities for Tandberg Linux Package files.
The technical implementation of this vulnerability stems from improper access control mechanisms within the administrative web interface of the VCS Expressway. When authenticated users navigate to specific administrative pages, the system fails to properly validate their authorization levels before permitting file upload operations. This flaw operates at the application layer and leverages the existing authentication mechanism to bypass intended security restrictions. The vulnerability is particularly concerning because it allows users to upload TLP files which are typically used for system updates and configuration changes, potentially enabling attackers to execute arbitrary code or modify system behavior. The bug ID CSCuw55651 indicates this was recognized by Cisco as a significant security issue within their internal tracking systems.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it creates a potential pathway for attackers to compromise the entire communication infrastructure managed by the VCS Expressway. Remote authenticated users can leverage this flaw to upload malicious TLP packages that may contain backdoors, rootkits, or other malicious components designed to persist on the system. The implications are particularly severe in enterprise environments where these devices often serve as critical communication hubs for video conferencing, collaboration, and business continuity. Successful exploitation could result in complete system compromise, unauthorized access to sensitive communications, and potential data exfiltration from the organization's network. The vulnerability affects the availability, integrity, and confidentiality of the communication services provided by the affected system.
Organizations should immediately implement mitigation strategies including applying the latest security patches released by Cisco to address this vulnerability. Network segmentation and monitoring of administrative access attempts should be enhanced to detect suspicious upload activities. Access controls should be reviewed to ensure users have only the minimum necessary privileges for their roles, following the principle of least privilege as recommended by the Center for Internet Security (CIS) benchmarks. Additionally, security teams should implement network-based intrusion detection systems to monitor for unauthorized file upload attempts and maintain detailed audit logs of administrative activities. The vulnerability aligns with CWE-284 which describes improper access control, and represents a clear violation of the ATT&CK framework's privilege escalation techniques where adversaries leverage existing credentials to gain higher privileges. Organizations should also consider implementing multi-factor authentication for administrative access and regular security assessments to identify similar authorization bypass vulnerabilities in their network infrastructure.