We propose CRYSTAL framework for automated cybersecurity assurance of cyber-physical systems (CPS) at design-time and runtime. We build attack models and apply formal verification to recognize potential attacks that may lead to security violations. We focus on both communication and computation in designing the attack models. We build a monitor to check and manage security at runtime and use a reference model, called Tiny Digital Twin, in detecting attacks. The Tiny Digital Twin is an abstract behavioral model that is automatically derived from the state space generated by model checking during design-time. Using CRYSTAL, we are able to systematically model and check complex coordinated attacks. In this paper we discuss the applicability of CRYSTAL in security analysis and attack detection for different case studies, Temperature Control System (TCS), Pneumatic Control System (PCS), and Secure Water Treatment System (SWaT). We provide a detailed description of the framework and explain how it works in different cases.

This paper presents a method for detecting cyber-attacks in cyber-physical systems using a monitor. The method employs an abstract model called Tiny Twin, which is built at design time and is used at runtime to detect inconsistencies. Tiny Twin is a state transition system that represents the observable behavior of the system from the monitor point of view. We model the behavior of the system in the Rebeca modeling language and use Afra model checker to generate the state space. The Tiny Twin is built automatically, by abstracting the state space while keeping the observable actions and preserving the trace equivalence. For doing that we had to solve the complexities in the state space introduced by time-shifts, nondeterministic assignments and abstraction of internal actions. We formally define the state space as Concise Rebeca Timed Transition System (CRTTS), and then map CRTTS to an LTS. The LTS is then fed to a tool to abstract away the non-observable actions.

There is a growing interest in using the Blockchain for resolving IoT security and trustworthiness issues existing in today's complex systems. Blockchain concerns trust in peer to peer networks by providing a distributed tamper-resistant ledger. However, the combination of these two emerging technologies might create new problems and vulnerabilities that attackers might abuse. In this paper, we aim to investigate the trust mechanism of Lightweight Scalable BlockChain (LSB), that is a Blockchain specifically designed for Internet of Things networks, to show that a malicious participant in a Blockchain architecture have possibility to pursue an On-Off attack and downgrade the integrity of the distributed ledger. We choose a remote software update process as an instance to represent this violation. Finally, using the actor-based language Rebeca, we provide a model of a system under attack and verify the described attack scenario.