Interleaving Jamming in Wi-Fi Networks

The increasing importance of Wi-Fi in today's wireless communication systems, both as a result of Wi-Fi offloading and its integration in IoT devices, makes it an ideal target for malicious attacks. In this paper, we investigate the structure of the combined interleaver/convolutional coding scheme of IEEE 802.11a/g/n. The analysis of the first and second-round permutations of the interleaver allows us to design deterministic jamming patterns across subcarriers that when de-interleaved results in an interference burst. We show that a short burst across carefully selected sub-carriers exceeds the error correction capability of Wi-Fi. We implemented this attack as a reactive interleaving jammer on the firmware of the low-cost HackRF SDR. Our experimental evaluation shows that this attack can completely block the Wi-Fi transmissions with jamming power less than 1% of the communication (measured at the receiver) and block 95% of the packets with less than 0.1% energy. Furthermore, it is at least 5dB and up to 15dB more power-efficient than jamming attacks that are unaware of the Wi-Fi interleaving structure.