Prevention of Aging Attacks: Malicious Nature of the Control Signal

In this paper, a security problem in control systems is studied. We consider a controller that transmits the control signal to an actuator. An attacker can compromise the controller in order to degrade the legitimate control signal. We investigate the prevention of attacks that lead to a premature aging of an actuator. We propose to limit the actuator's output range in order to guarantee its normal aging's behavior. To do so, we propose an invariant set-based approach for restraining the control input set. We provide mathematical tools, in term of Linear Matrix Inequalities (LMIs), for quantifying the invariant set of continuous-time deterministic Linear Time-Invariant (LTI) system with compact control input set. The proposed algorithm involves several convex optimization problems reduced to solving semidefinite programs (SDPs) for restraining the control input set for preventing aging attacks. A motor premature aging simulation example is presented to illustrate the performance of the proposed algorithm and shown the limits of the proposed algorithm.

I. Introduction

For several decades, digital controllers and digital communication networks have increasingly been present in control systems applications. Control systems are now mostly computer-based systems with reconfiguration capabilities that monitor and control the plant with sensors and actuators. For over a decade, digital controllers have been the targets of attackers. Once they gained access to the control system, they took over control of the actuators by manipulating the control signals issued from the digital controllers [1] .