Digital radio signal cancellation attacks: an experimental evaluation

Attacker models are the cornerstone of any security assessment. As attacker's capabilities evolve over time, it is key to re-evaluate periodically if attacker models that were deemed unrealistic in the past might not pose a possible threat today. In this work, we evaluate the threat of wireless radio signal cancellation attacks in the face of recent advancements in software-defined radio attacker capabilities. Unlike classical radio interference or jamming attacker models which add noise to the legitimate communication, signal cancellation attacks aim at interfering destructively with the legitimate signal in order to remove those signals from the spectrum. While signal cancellation attacks were deemed unrealistic in the analogue domain, we analyse the system requirements to perform such attacks digitally using SDRs and evaluate the feasibility to launch such attacks against wireless communication systems such as GPS. Our evaluation reveals that signal cancellation attacks that manage to attenuate up to 40 dB of the signal at the receiver are feasible over the air. We further show that even complex CDMA signals such as GPS can be attenuated by 30 dB, even below a receiver's noise floor. These results indicate that digital signal cancellation attacks - especially against systems like GPS - should not be considered impossible per se, but deserve consideration when assessing the threat of attacks on wireless communication systems.