4 research outputs found

    On Decidability of Existence of Nonblocking Supervisors Resilient to Smart Sensor Attacks

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    Cybersecurity of discrete event systems (DES) has been gaining more and more attention recently, due to its high relevance to the so-called 4th industrial revolution that heavily relies on data communication among networked systems. One key challenge is how to ensure system resilience to sensor and/or actuator attacks, which may tamper data integrity and service availability. In this paper we focus on some key decidability issues related to smart sensor attacks. We first present a sufficient and necessary condition that ensures the existence of a smart sensor attack, which reveals a novel demand-supply relationship between an attacker and a controlled plant, represented as a set of risky pairs. Each risky pair consists of a damage string desired by the attacker and an observable sequence feasible in the supervisor such that the latter induces a sequence of control patterns, which allows the damage string to happen. It turns out that each risky pair can induce a smart weak sensor attack. Next, we show that, when the plant, supervisor and damage language are regular, it is computationally feasible to remove all such risky pairs from the plant behaviour, via a genuine encoding scheme, upon which we are able to establish our key result that the existence of a nonblocking supervisor resilient to smart sensor attacks is decidable. To the best of our knowledge, this is the first result of its kind in the DES literature on cyber attacks. The proposed decision process renders a specific synthesis procedure that guarantees to compute a resilient supervisor whenever it exists, which so far has not been achieved in the literature.Comment: 14 pages, 11 figure

    Localizaci贸n de fallas en microredes el茅ctricas basado en un modelo Markoviano.

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    The present paper analyzes the effect produced by the appearance of a state or failure event on the system and its environment, component or control structure from the result of algorithms of fault location or FDIs for Electric Microgrids, using a Markovian model. This method will help to understand the propagation of faults and their effect on the Microgrids, in addition to allowing the identification and location of the important faults and its control with fault tolerance techniques. This method not only implements a fault location algorithm, it also achieves a scheme to analyze the fault propagation that occur in Microgrids (MG). For this case, fault locations, the detection of critical points in which a failure can occur, as well as the determination of the most probable route for its propagation, are considered the aim to be resolved. The model was created using the Markov process. It is important to consider that in order for the Markov process to obtain results close to reality, it is necessary to consider not only a model that simulates the dynamic behavior of the system, but also to have more in-depth studies that provide statistical and probabilistic data on failure events, their propagation and decision making once located.El presente trabajo analiza el efecto producido por la aparici贸n de un estado o evento de fallo sobre el sistema y su entorno, componente o estructura de control usando un modelo Markoviano, y a partir del resultado de algoritmos de localizaci贸n de fallas o FDIs para Microredes El茅ctrica. El m茅todo ayudar谩 a comprender la propagaci贸n de fallas y su efecto en las Micro-redes, permitiendo adem谩s identificar y localizar las fallas importantes a tratar y controlar con t茅cnicas de tolerancia a fallas. Este m茅todo no solo implementa un algoritmo de localizaci贸n de falla, adem谩s logra un esquema para analizar la propagaci贸n de las fallas que se presentan en Micro-redes (MG). Para el caso propuesto, la localizaci贸n de la falla, la detecci贸n de los puntos cr铆ticos en los que puede ocurrir una falla, as铆 como la determinaci贸n de la ruta m谩s probable para la propagaci贸n de las mismas, son considerados como un punto clave a resolver. Es importante considerar que, para que el proceso de Markov obtenga resultados cercanos a la realidad es necesario considerar no solo un modelo que simule el comportamiento din谩mico del sistema, tambi茅n, contar con estudios m谩s profundos que brinden datos estad铆sticos y probabil铆sticos de los eventos de fallos, su propagaci贸n, y toma de decisiones una vez que estos son localizados

    A cyber attack model with bounded sensor reading alterations

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    One of the major challenges about cyber physical systems is how to prevent cyber attacks to ensure system integrity. There has been a large number of different types of attacks discussed in the modern control and computer science communities. In this paper we aim to investigate one special type of attacks in the discrete-event system framework, where an attacker can arbitrarily alter sensor readings after intercepting them from a target system in order to trick a given supervisor to issue control commands improperly, driving the system to an undesirable state. We first consider the cyber attack problem from an attacker point of view, and formulate an attack with bounded sensor reading alterations (ABSRA) problem. We then show that the supremal (or least restrictive) ABSRA exists and can be synthesized, as long as the plant model and the supervisor model are regular, i.e., representable by finite-state automata.MOE (Min. of Education, S鈥檖ore)Accepted versio
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