On the Robustness of Wi-Fi Deauthentication Countermeasures

With the introduction of WPA3 and Wi-Fi 6, an increased usage of Wi-Fi Management Frame Protection (MFP) is expected. Wi-Fi MFP, defined in IEEE 802.11w, protects robust management frames by providing data confidentiality, integrity, origin authenticity, and replay protection. One of its key goals is to prevent deauthentication attacks in which an adversary forcibly disconnects a client from the network. In this paper, we inspect the standard and its implementations for their robustness and protection against deauthentication attacks. In our standard analysis, we inspect the rules for processing robust management frames on their completeness, consistency, and security, leading to the discovery of unspecified cases, contradictory rules, and revealed insecure rules that lead to new denial-of-service vulnerabilities. We then inspect implementations and identify vulnerabilities in clients and access points running on the latest versions of the Linux kernel, hostap, IWD, Apple (i.e., macOS, iOS, iPadOS), Windows, and Android. Altogether, these vulnerabilities allow an adversary to disconnect any client from personal and enterprise networks despite the usage of MFP. Our work highlights that management frame protection is insufficient to prevent deauthentication attacks, and therefore more care is needed to mitigate attacks of this kind. In order to address the identified shortcomings, we worked with industry partners to propose updates to the IEEE 802.11 standard.