Orthogonality-Sabotaging Attacks against OFDMA-based Wireless Networks

Wireless jamming remains as one of the primary threats towards wireless security. Traditionally, jamming is able to disrupt wireless signals within, but not beyond, its covered bandwidth. In this paper, we propose a novel attack strategy, called orthogonality-sabotaging attack, against orthogonal frequency division multiple access (OFDMA) that has been widely adopted in today's wireless network standards (e.g., 4G/5G and 802.11ax). The attack intentionally introduces an unaligned narrowband jamming signal to an OFDMA network so as to destroy the orthogonality among all subcarriers in broadband signals. We theoretically formulate and optimize the attack strategies, and then use real-world experiments to show that orthogonality sabotaging is very efficient and can take down an 802.11ax network with only 1/5-1/4 of the full network bandwidth. Finally, we propose an attack identification and localization method to identify and localize orthogonality-sabotaging attacks in the fullband spectrum with 92% overall accuracy and localization errors within about 0.4 subcarrier spacing in experiments.