CVE-2017-12311 in Meeting Server
Summary
by MITRE
A vulnerability in the H.264 decoder function of Cisco Meeting Server could allow an unauthenticated, remote attacker to cause a Cisco Meeting Server media process to restart unexpectedly when it receives an illegal H.264 frame. The vulnerability is triggered by an H.264 frame that has an invalid picture parameter set (PPS) value. An attacker could exploit this vulnerability by sending a malformed H.264 frame to the targeted device. An exploit could allow the attacker to cause a denial of service (DoS) condition because the media process could restart. The media session should be re-established within a few seconds, during which there could be a brief interruption in service. Cisco Bug IDs: CSCvg12559.
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Analysis
by VulDB Data Team • 01/24/2021
The vulnerability identified as CVE-2017-12311 resides within the H.264 decoder functionality of Cisco Meeting Server, representing a critical weakness that enables remote attackers to induce unauthorized service disruption. This flaw specifically targets the media processing components responsible for handling H.264 video streams, which are fundamental to the server's operation in facilitating video conferencing and collaboration services. The vulnerability manifests when the system receives malformed H.264 frames containing invalid picture parameter set values, triggering an unexpected restart of the media process that governs video stream handling.
The technical exploitation mechanism of this vulnerability operates through the manipulation of H.264 frame structures, specifically targeting the picture parameter set elements that define video encoding parameters. When an attacker crafts and transmits an H.264 frame with an invalid PPS value, the Cisco Meeting Server's decoder fails to properly validate the input data, resulting in a process crash that necessitates automatic restart. This behavior aligns with CWE-122, which describes buffer overflow vulnerabilities, and represents a classic example of improper input validation where the system does not adequately sanitize incoming media data before processing. The vulnerability's remote nature means that attackers can exploit it without requiring authentication, making it particularly dangerous in networked environments where video conferencing systems are exposed to external traffic.
The operational impact of this vulnerability extends beyond simple service interruption, as it creates opportunities for sustained disruption of critical communication infrastructure. During the media process restart, users experience brief service interruptions that can range from seconds to minutes depending on the system's recovery mechanisms and network conditions. This disruption affects real-time collaboration sessions, potentially compromising business continuity and communication workflows that depend on the Cisco Meeting Server for video conferencing capabilities. The vulnerability's potential for repeated exploitation means that attackers could maintain ongoing disruption of service, transforming a single incident into a persistent threat to system availability. From an operational security perspective, this represents a significant concern for organizations that rely on continuous video conferencing services for remote collaboration, telepresence, and business-critical communications.
Mitigation strategies for CVE-2017-12311 should prioritize immediate implementation of vendor-provided security patches and firmware updates that address the specific H.264 decoder validation issues. Network segmentation and access control measures can help limit exposure by restricting direct access to the Cisco Meeting Server from untrusted networks, while monitoring systems should be deployed to detect anomalous H.264 frame patterns that might indicate attempted exploitation. Organizations should also consider implementing intrusion detection systems specifically configured to identify malformed video stream data that could indicate exploitation attempts. The vulnerability's characteristics align with ATT&CK technique T1499.004, which covers network disruption via resource exhaustion, and organizations should incorporate this into their broader cybersecurity frameworks. Additionally, regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other media processing components, while incident response procedures should be updated to address potential DoS conditions related to media processing failures.