CVE-2015-4317 in TelePresence Video Communication Server
Summary
by MITRE
Cisco TelePresence Video Communication Server (VCS) Expressway X8.5.2 allows remote attackers to cause a denial of service via invalid variables in an authentication packet, aka Bug ID CSCuv40469.
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Analysis
by VulDB Data Team • 06/12/2022
The vulnerability identified as CVE-2015-4317 affects Cisco TelePresence Video Communication Server (VCS) Expressway version 8.5.2, representing a critical denial of service weakness that can be exploited remotely by attackers. This flaw resides in the authentication packet processing mechanism of the VCS Expressway software, where the system fails to properly validate input variables during the authentication process. The vulnerability specifically manifests when the system receives malformed or invalid variables within authentication packets, leading to unexpected behavior and potential system instability.
The technical implementation of this vulnerability stems from insufficient input validation and error handling within the authentication subsystem of the VCS Expressway. When an attacker crafts malicious authentication packets containing invalid variables, the system attempts to process these inputs without adequate sanitization measures. This processing failure results in the system becoming unresponsive or crashing, effectively rendering the communication server unavailable to legitimate users. The flaw operates at the protocol level where authentication requests are handled, making it particularly dangerous as it can be exploited without requiring authentication credentials or prior access to the system. The vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic example of how malformed input can lead to system instability and denial of service conditions.
The operational impact of this vulnerability extends beyond simple service disruption, as it can severely compromise the availability of video communication services within organizations that rely on Cisco VCS Expressway systems. Organizations using this software for critical business communications, teleconferencing, and remote collaboration may experience significant operational disruptions when attackers exploit this weakness. The remote exploit capability means that attackers can target systems from outside the network perimeter, potentially affecting organizations with limited network segmentation or inadequate monitoring controls. This vulnerability undermines the reliability of the communication infrastructure and can result in lost productivity, missed business opportunities, and potential financial losses. The impact is particularly severe in environments where video conferencing is mission-critical, such as healthcare facilities, financial institutions, or government agencies that depend on secure communication channels.
Mitigation strategies for CVE-2015-4317 should prioritize immediate patch management with the latest Cisco security updates, as the vendor has released fixes for this vulnerability. Network administrators should implement strict access controls and monitor authentication traffic for suspicious patterns that may indicate exploitation attempts. The implementation of intrusion detection systems and network monitoring tools can help identify malformed authentication packets before they can cause system instability. Organizations should also consider network segmentation to limit the potential impact of exploitation and implement rate limiting on authentication requests to reduce the effectiveness of automated attack tools. According to ATT&CK framework, this vulnerability falls under the T1499 category for Network Denial of Service, and organizations should consider implementing defensive measures such as network traffic filtering and authentication protocol hardening to prevent exploitation. Regular vulnerability assessments and security audits should be conducted to identify similar weaknesses in other network components that may present analogous attack vectors.