Countering Relay and Spoofing Attacks in the Connection Establishment Phase of Wi-Fi Systems
Naureen Hoque, Hanif Rahbari · 2023
To establish a secure Wi-Fi connection, a station first exchanges several unprotected management frames with an access point (AP) to eventually authenticate each other and install a pairwise key. It is, therefore, possible for an adversary to spoof elements of those unprotected frames at the physical (PHY) or MAC layers, facilitating additional attacks (e.g., man-in-the-middle and starvation attacks). Despite a few ad hoc efforts, there is still no practical way to counter these attacks jointly. In this paper, we propose practical schemes to employ cryptography at the PHY layer combined with a time-bound technique to detect and mitigate such attacks in enterprise and 802.1X-based public networks. Our backward-compatible schemes embed a digital signature of the AP (or a message authentication code) in frame preamble signals and add only a negligible delay to the connection establishment process and achieve a 98.9% true positive rate in detecting an attacker who tries to relay valid preambles. Furthermore, we conduct a formal security analysis of our scheme using a model checker and a cryptographic protocol verifier and evaluate its performance in a commercial AP-and-USRP~testbed.