Securing OFDM-Based ISAC Systems Against Sensing Attacks

Integrated communications and sensing (ISAC) has emerged as a core capability in next-generation wireless networks (NextG), providing numerous advantages in spectral efficiency, performance, and hardware cost. However, using communication waveforms for sensing leaves ISAC systems vulnerable to sensing attacks, as such waveforms are not designed with sensing security in mind. In this paper, we investigate the security of ISAC systems against sensing attacks. We focus on OFDM due to its widespread adoption. We theoretically and experimentally demonstrate that OFDM-based sensing is vulnerable to target spoofing and elimination attacks that can alter the perception of the physical environment. Such attacks are launched online by exploiting the known structure of OFDM waveforms. To counter sensing attacks, we design waveform randomization methods that exploit the flexible 5G/NextG numerology to implement a moving target defense strategy. We analyze the security of the proposed attack detection method and demonstrate that online attackers are detected with high probability. We validate the security and communication/sensing performance of our methods in a 28 GHz mm Wave testbed by implementing the ISAC functionality, the sensing attacks, and the proposed countermeasures.