CVE-2017-6763 in Meeting Server
Summary
by MITRE
A vulnerability in the implementation of the H.264 protocol in Cisco Meeting Server (CMS) 2.1.4 could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected system. The vulnerability exists because the affected application does not properly validate Fragmentation Unit (FU-A) protocol packets. An attacker could exploit this vulnerability by sending a crafted H.264 FU-A packet through the affected application. A successful exploit could allow the attacker to cause a DoS condition on the affected system due to an unexpected restart of the CMS media process on the system. Although the CMS platform continues to operate and only the single, affected CMS media process is restarted, a brief interruption of media traffic for certain users could occur. Cisco Bug IDs: CSCve10131.
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Analysis
by VulDB Data Team • 01/07/2021
The vulnerability identified as CVE-2017-6763 resides within Cisco Meeting Server version 2.1.4 and represents a critical denial of service weakness in the H.264 video streaming protocol implementation. This flaw specifically targets the Fragmentation Unit (FU-A) packet handling mechanism, which is a standard component of the H.264 protocol used for transmitting video data across network connections. The vulnerability stems from insufficient input validation within the CMS media processing subsystem, creating an exploitable condition that allows remote attackers to manipulate the system's behavior through specially crafted protocol packets.
The technical implementation of this vulnerability occurs when the affected Cisco Meeting Server receives malformed H.264 FU-A packets that exceed normal protocol boundaries or contain unexpected data structures. According to CWE-20, this represents a classic input validation error where the system fails to properly sanitize incoming data before processing it. The CMS application processes these malformed packets without adequate boundary checking or data sanitization, leading to a crash in the media processing component. This behavior aligns with ATT&CK technique T1499.004 which describes denial of service attacks targeting network infrastructure components. The system's failure mode manifests as an unexpected restart of the CMS media process, which temporarily disrupts video conferencing services for users connected to the affected system.
The operational impact of this vulnerability extends beyond simple service interruption, as it affects the reliability and availability of enterprise communication systems. While the overall CMS platform remains operational, the restart of individual media processes creates brief but noticeable disruptions in video streaming for conference participants. This degradation in service quality can significantly impact business operations, particularly in environments where continuous video conferencing is critical for collaboration. The vulnerability's remote exploitability means that attackers can trigger the DoS condition without requiring authentication or physical access to the system, making it particularly dangerous in networked environments where the CMS server is exposed to external traffic. Organizations utilizing Cisco Meeting Server 2.1.4 face potential business disruption ranging from temporary audiovisual service interruptions to more severe impacts on productivity during critical meetings.
Mitigation strategies for CVE-2017-6763 should prioritize immediate patch deployment through Cisco's official security advisories, as the vendor has released firmware updates addressing the specific input validation issues in the H.264 protocol implementation. Network administrators should implement additional protective measures such as ingress filtering to block malformed H.264 packets at network boundaries, particularly at the firewall or network access control points. The implementation of intrusion detection systems capable of identifying suspicious H.264 packet patterns can provide early warning of potential exploitation attempts. Organizations should also consider implementing process monitoring solutions that can automatically detect and restart affected media processes, minimizing service disruption during exploitation attempts. Furthermore, network segmentation strategies should be employed to isolate the CMS infrastructure from less secure network zones, reducing the attack surface available to potential adversaries. Regular vulnerability assessments and penetration testing should be conducted to identify similar implementation flaws in other network infrastructure components that may be vulnerable to similar protocol-based attacks.