  Electric Vehicle (EV) has become one of the promising solutions to the
ever-evolving environmental and energy crisis. The key to the wide adoption of
EVs is a pervasive charging infrastructure, composed of both private/home
chargers and public/commercial charging stations. The security of EV charging,
however, has not been thoroughly investigated. This paper investigates the
communication mechanisms between the chargers and EVs, and exposes the lack of
protection on the authenticity in the SAE J1772 charging control protocol. To
showcase our discoveries, we propose a new class of attacks, ChargeX, which
aims to manipulate the charging states or charging rates of EV chargers with
the goal of disrupting the charging schedules, causing a denial of service
(DoS), or degrading the battery performance. ChargeX inserts a hardware attack
circuit to strategically modify the charging control signals. We design and
implement multiple attack systems, and evaluate the attacks on a public
charging station and two home chargers using a simulated vehicle load in the
lab environment. Extensive experiments on different types of chargers
demonstrate the effectiveness and generalization of ChargeX. Specifically, we
demonstrate that ChargeX can force the switching of an EV's charging state from
``stand by" to ``charging", even when the vehicle is not in the charging state.
We further validate the attacks on a Tesla Model 3 vehicle to demonstrate the
disruptive impacts of ChargeX. If deployed, ChargeX may significantly demolish
people's trust in the EV charging infrastructure.
