CVE-2016-6824 in AC6003
Summary
by MITRE
Huawei AC6003, AC6005, AC6605, and ACU2 access controllers with software before V200R006C10SPC200 allows remote authenticated users to cause a denial of service (device restart) via crafted CAPWAP packets.
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Analysis
by VulDB Data Team • 04/24/2019
The vulnerability identified as CVE-2016-6824 affects Huawei AC6003, AC6005, AC6605, and ACU2 access controllers running firmware versions prior to V200R006C10SPC200. This represents a significant security flaw that enables remote authenticated attackers to induce a denial of service condition by sending specially crafted CAPWAP packets to the affected devices. The vulnerability resides in the improper handling of CAPWAP protocol messages within the wireless access controller software stack, creating an exploitable condition that can result in complete device restarts. The impact extends beyond simple service disruption as these access controllers serve as critical infrastructure components for wireless network management and user authentication within enterprise and service provider environments.
The technical root cause of this vulnerability stems from inadequate input validation and error handling mechanisms within the CAPWAP packet processing functionality of the affected Huawei access controllers. When legitimate authenticated users send malformed CAPWAP packets to the device, the system fails to properly validate the packet structure and content before processing. This leads to memory corruption or unexpected state transitions that ultimately trigger an automatic device reboot. The flaw operates at the protocol level, specifically targeting the CAPWAP (Control And Provisioning of Wireless Access Points) implementation that governs communication between wireless access points and the central access controller. This vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities in heap-based memory allocation.
The operational impact of this vulnerability presents severe consequences for network availability and business continuity. When exploited, the denial of service condition causes complete disruption of wireless network services as the access controller restarts and re-establishes connections with connected wireless access points. Network administrators face the challenge of maintaining service availability while the device recovers from the restart event, which can take several minutes to complete. In enterprise environments, this vulnerability can affect thousands of wireless users simultaneously, while service providers may experience widespread disruption across multiple locations. The authenticated nature of the attack means that only users with valid credentials can exploit the vulnerability, though this still represents a significant risk since legitimate users may be compromised or malicious insiders could leverage this weakness. The vulnerability also impacts the overall network security posture by creating potential for extended service disruption and providing attackers with a method to degrade network infrastructure reliability.
Mitigation strategies for CVE-2016-6824 should prioritize immediate firmware updates to the affected Huawei access controller models to the patched versions V200R006C10SPC200 or later. Network administrators should also implement network segmentation and access controls to limit the scope of potential exploitation by restricting CAPWAP traffic to trusted network segments only. Monitoring and logging of CAPWAP traffic should be enhanced to detect anomalous packet patterns that may indicate exploitation attempts. Additionally, implementing network intrusion detection systems with signature-based detection for known CAPWAP attack patterns can help identify and block malicious traffic before it reaches the vulnerable devices. Organizations should also consider implementing redundant access controller deployments to minimize the impact of single-point failures. The vulnerability demonstrates the importance of maintaining current firmware versions and conducting regular security assessments of network infrastructure components, particularly those handling critical protocols like CAPWAP that govern wireless network operations. This vulnerability also aligns with ATT&CK technique T1499.002, which describes network disruption attacks, and T1566.001, which covers spearphishing with social engineering techniques that may be used to gain initial access to network credentials.