CVE-2020-3497 in IOS XE
Summary
by MITRE
Multiple vulnerabilities in the Control and Provisioning of Wireless Access Points (CAPWAP) protocol processing of Cisco IOS XE Software for Cisco Catalyst 9800 Series Wireless Controllers could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition of an affected device. These vulnerabilities are due to insufficient validation of CAPWAP packets. An attacker could exploit these vulnerabilities by sending a malformed CAPWAP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to crash and reload, resulting in a DoS condition on the affected device.
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Analysis
by VulDB Data Team • 09/25/2020
The vulnerability identified as CVE-2020-3497 affects Cisco IOS XE Software running on Cisco Catalyst 9800 Series Wireless Controllers, specifically targeting the Control and Provisioning of Wireless Access Points (CAPWAP) protocol implementation. This represents a critical security flaw that undermines the stability and availability of wireless network infrastructure. The CAPWAP protocol serves as the foundational communication mechanism between wireless access points and wireless controllers, making this vulnerability particularly dangerous as it directly impacts the core functionality of enterprise wireless networks. The affected devices operate in environments where continuous network availability is paramount, making any denial of service condition potentially disruptive to business operations.
The technical root cause of this vulnerability stems from inadequate input validation within the CAPWAP packet processing logic of the affected Cisco IOS XE software versions. When processing incoming CAPWAP packets, the software fails to properly validate packet structures, lengths, and content, creating opportunities for malformed packets to bypass normal security checks. This insufficient validation allows an attacker to craft specially designed CAPWAP packets that exploit memory handling weaknesses in the processing stack. The vulnerability specifically affects the parsing and validation mechanisms that should ensure packet integrity before processing, leaving the system susceptible to crafted payloads that trigger unexpected behavior in the network controller's memory management subsystem.
The operational impact of exploiting CVE-2020-3497 manifests as a complete denial of service condition on the affected wireless controller, causing the device to crash and automatically reload its operating system. This reload process results in temporary network disruption as the controller reinitializes its wireless services and reconnects to managed access points. For organizations relying on Cisco Catalyst 9800 Series controllers, this vulnerability could lead to significant service interruptions affecting wireless connectivity for numerous users across the enterprise network. The adjacent network access requirement means that attackers must be physically present on the same network segment as the target device, but this limitation does not mitigate the potential impact on critical network infrastructure.
Security professionals should consider this vulnerability in the context of the ATT&CK framework, particularly under the T1499 category for Network Denial of Service, where the attack vector involves exploitation of protocol implementations. The weakness aligns with CWE-20, "Improper Input Validation," and CWE-125, "Out-of-Bounds Read," as the insufficient validation leads to memory access violations. Organizations should implement immediate mitigations including network segmentation to limit physical access to wireless controllers, deployment of access control lists to filter CAPWAP traffic, and application of Cisco's recommended security patches. The vulnerability also highlights the importance of network device monitoring and alerting systems that can detect unusual restart patterns or network disruptions that may indicate exploitation attempts.
Cisco has addressed this vulnerability through multiple software releases and security advisories, emphasizing the need for prompt patch management across all affected devices. The vulnerability demonstrates the critical importance of validating protocol implementations in network infrastructure devices, as flaws in core communication protocols can have cascading effects throughout enterprise networks. Organizations should conduct comprehensive vulnerability assessments of their wireless infrastructure and implement layered security controls to protect against similar protocol-level vulnerabilities that could potentially be exploited by adjacent attackers.