Seeing the Unseen: The REVEAL Protocol to Expose the Wireless Man-in-the-Middle

A Man-in-the-Middle (MiM) can collect over-the-air packets whether from a mobile or a base station, process them, possibly modify them, and forward them to the intended receiver. This paper exhibits the REVEAL protocol that can detect a MiM, whether it has half-duplex capability, full-duplex capability, or double full-duplex capability. The REVEAL protocol creates a sequence of timing-based challenge packets where the transmission times of the packets, their durations, and their frequencies, are chosen to create conflicts at the MiM, and make it impossible for the MiM to function. Implementing the REVEAL protocol in 4G/5G technology, we instantiate a MiM between the 4G/5G base station and a mobile, and exhibit the successful detection mechanisms. With the shared source code, the MiM can be reproduced using software defined radios and protocol efficacy can be verified using any open software defined cellular networks with off-the-shelf devices.