CVE-2020-3399 in IOS XE
Summary
by MITRE
A vulnerability 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, remote attacker to cause a denial of service (DoS) condition of an affected device. The vulnerability is due to insufficient input validation during CAPWAP packet processing. An attacker could exploit this vulnerability by sending a crafted CAPWAP packet to an affected device, resulting in a buffer over-read. 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-2020-3399 resides within the Control and Provisioning of Wireless Access Points protocol implementation of Cisco IOS XE Software running on Cisco Catalyst 9800 Series Wireless Controllers. This represents a critical security flaw that affects the foundational communication protocols used to manage wireless access points in enterprise networks. The CAPWAP protocol serves as the primary mechanism for wireless controllers to communicate with wireless access points, making this vulnerability particularly concerning for organizations relying on these devices for network infrastructure management. The affected controllers operate as central management points for wireless networks, controlling authentication, configuration, and monitoring of connected access points across enterprise environments.
The technical root cause of this vulnerability stems from inadequate input validation mechanisms within the CAPWAP packet processing logic of the affected software implementation. Specifically, the software fails to properly validate the size and structure of incoming CAPWAP packets before processing them, creating a buffer over-read condition. This flaw occurs when the system attempts to read data from memory locations beyond the allocated buffer boundaries, typically triggered by malformed or crafted packet structures. The vulnerability manifests during the parsing of CAPWAP protocol headers and payload data, where the software does not adequately verify that incoming packet sizes remain within expected parameters. This weakness aligns with common software security principles where insufficient bounds checking leads to memory corruption vulnerabilities.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire wireless infrastructure management capability of affected organizations. An unauthenticated remote attacker can exploit this weakness by transmitting a specially crafted CAPWAP packet to the vulnerable device, triggering an immediate system crash and subsequent automatic reload process. This DoS condition effectively renders the wireless controller inoperable until manual intervention or automatic recovery occurs, disrupting wireless network connectivity for all connected devices. The severity of impact is compounded by the fact that the attack requires no authentication credentials, making it accessible to any remote network entity capable of reaching the controller's management interface. Organizations may experience extended downtime during the recovery process, potentially affecting business operations and requiring manual intervention to restore wireless services.
Mitigation strategies for CVE-2020-3399 should prioritize immediate software updates from Cisco to address the underlying input validation issues. Network administrators should implement network segmentation to limit direct access to wireless controller management interfaces, reducing the attack surface available to potential threat actors. The implementation of intrusion detection systems capable of identifying and blocking malformed CAPWAP traffic patterns can provide additional defense layers. Organizations should also consider disabling unnecessary CAPWAP functionality when not required and establish monitoring procedures to detect unusual controller behavior that may indicate exploitation attempts. According to CWE standards, this vulnerability maps to CWE-121 for stack-based buffer overflow conditions, while ATT&CK framework categorizes this as a network service exploitation technique under the Tactic of Execution and the Technique of Exploitation for Privilege Escalation. The vulnerability demonstrates the critical importance of input validation in network protocol implementations, particularly for devices that serve as central management points in enterprise infrastructure.