Crafting Adversarial Attacks to MU-MIMO OFDMA Transmissions in Wi-Fi Networks

The exponential growth of Wi-Fi-enabled devices and the changing nature of online activities highlight the urgent need to find innovative solutions to solve the ever-growing spectrum crunch. To address this challenge, the IEEE 802.11ax standard breaks away from traditional approaches leveraged in previous standards by jointly enabling orthogonal frequency-division multiple-access (OFDMA) and multi-user MIMO (MU-MIMO). While IEEE standardization groups are working to increase the network capacity (IEEE 802.11be) and its reliability (IEEE 802.11bn), there are still serious security issues in Wi-Fi. Some recent work has revealed that MU-MIMO transmissions can be thwarted by a malicious user that interferes with the procedure followed to set up simultaneous transmissions to multiple stations (STAs). In this work, we show that a similar attack is also effective in OFDMA MU-MIMO transmissions. Specifically, a malicious user in the network can alter the precoding procedure by transmitting adversarial feedback during the channel sounding phase, thus increasing the bit error rate (BER) experienced by legitimate STAs to up to 0.5 depending on the portion of feedback that is poisoned. We shared the code to implement our attack for reproducibility purposes and to ease its integration into digital twin frameworks of Wi-Fi networks to study and evaluate effective countermeasures.