Industrial control systems have been frequent targets of cyber attacks during the last decade. Adversaries can hinder the safe operation of these systems by tampering with their sensors and actuators, while ensuring that the monitoring systems are not able to detect such attacks in time. In this talk, we present methods to design and overcome stealthy attacks on linear time-invariant control systems that estimate their state using an interval estimator, in the presence of unknown but bounded noise and perturbations. We analyze scenarios in which a malicious agent compromises the sensors and/or the actuators of the system with additive attack signals to steer the state estimate outside of the bounds provided by the interval estimator. We first show that maximally disruptive attack sequences that remain undetected by a linear monitor can be computed recursively via linear programming. We then present the design of an attack-resilient interval estimator for the system’s state, identifying sufficient conditions on the sensor data for such an observer to be realizable. We propose a computational method to determine optimal observer gains using semi-definite programming and compute bounds for the unknown attack signal as well. In numerical simulations, we illustrate and compare the ability of such interval estimators to still provide accurate estimates when under attack.
Kwassi Degue is a Postdoctoral Associate in the Department of Aeronautics and Astronautics (AeroAstro) at Massachusetts Institute of Technology (MIT). He is affiliated with the Dynamics, Infrastructure Networks, and Mobility (DINaMo) Research Group, advised by Prof. Hamsa Balakrishnan. He received the Dipl. Eng. degree from Ecole Nationale Superieure d’Ingenieurs, Togo, in 2011, the M.Sc. degree in automatic control from the University of Lille, France, in 2015 and the Ph.D. degree in Electrical Engineering from Ecole Polytechnique de Montreal, Canada, in 2021. He was a Visiting Researcher at MIT from February to May 2020. From April 2017 to April 2018 and from October 2018 to October 2019, he was a Visiting Researcher at Georgia Institute of Technology and at the Technical University of Munich (TUM). His research interests include privacy-preserving information processing, security in cyber-physical systems, stability analysis, observer design and control of uncertain nonlinear and linear systems, with applications to intelligent infrastructure systems and air traffic management. He is also a part-time Senior Consultant (Data Privacy Expert) at DevTech Systems, Inc. and at the United States Agency for International Development (USAID).
Kwassi was a recipient of one U.S. Rising Star in Aerospace award in 2021, the Mitacs Globalink Research Award in 2020, the FRQNT (The Fonds de recherche du Quebec-Nature et technologies) doctoral excellence scholarship from 2019 to 2020 and the Fondation Pierre Arbour doctoral excellence and leadership scholarship from 2018 to 2020. He was also a recipient of the DAAD (The German Academic Exchange Service) research fellowship in 2018, the FRQNT International Doctoral Internships-Energy/Digital/Aerospace Merit Fellowship from 2017 to 2018 and the European Commission’s Erasmus Mundus Master Scholarship for outstanding students from African countries from 2013 to 2015.
Galois was pleased to host this tech talk via live-stream for the public. A video of the presentation can be found above.