  In pursuance to understand the behavior of a potential green hybrid attacker
in secure internet-of-things (IoT), this letter investigates optimal energy
utilization from the attacker's viewpoint. Specifically, we propose a novel
framework for optimizing the efficacy of a hybrid attacker, possessing
capability to both eavesdrop and jam, while considering the underlying energy
consumption. In particular, we maximize the attacker energy efficiency (AEE) in
secure IoT by deriving the analytical solutions for jointly global-optimal
attacking mode, eavesdropping rate, and jamming power. Numerical results,
validating analytical claims, reveal that the proposed green design can offer
about 45% improvement in average AEE over the relevant benchmarks.
