Resilient Cyber Physical Systems

A cyber physical system (CPS) is defined as a system involving the close integration of the system’s cyber (computational and communications) and physical components. Ideally, the tight coordination of the cyber and physical elements enables greater autonomy, efficiency, functionality, reliability, adaptability and usability. CPSs are typically considered to be “next generation” systems that will evolve from current generation embedded systems, sensor networks, robotics, energy systems and medical technology among other application spaces.

The Need for Security

The security of these systems must be addressed for a number of reasons. First, many envisioned CPSs will be used for critical decision-making and will affect human and societal welfare at different scales making it imperative that these systems be trustworthy, robust and reliable. For example, the emerging smart grid is a CPS involving bidirectional energy and information flow. The security and resilience of this critical infrastructure is of paramount importance. Similarly, technologies for robotic surgery must be trustworthy given their crucial application to healthcare and human welfare. Second, the tight coupling of cyber-physical components results in a highly information technology-intertwined system which is vulnerable to cyber attack on many scales. These attacks may be commonly known or even readily available online. Thus, CPSs provide greater opportunities for malicious opponents. Third, many CPS application areas such as the field of electric power systems are governed with cyber security guidelines and standards. For example, new “smart” technologies integrated by electric power utilities (EPUs) must be security-compliant. Thus, to be able to gain market share, vendors of secure CPS  technologies must account for security in their subsystems design and development.

Vision

Secure cyber physical systems are envisioned to 1) provide robust control and communications, 2) be self- and situationally-aware in real-time, 3) provide continuous (but possibly limited) service under persistent attacks and failures, and 4) work cooperatively with shared defenses and understanding. Such functionality enables a cyber physical system to operate with the purpose for which it was procured even in the presence of malicious parties and/or adversarial efforts. This requires multidisciplinary support for security solutions that are autonomous, cooperative, efficient, reconfigurable, resilient, robust and scalable. And thus a deep understanding of the cyber interactions and infrastructure physics on a common semantic basis is needed to understand information flow and physical dependencies detrimental to operation.

The current generation of CPS-like systems demonstrates a large degree of decoupling. Cyber and physical elements are distinct and approaches to securing these systems are not holistic. This creates a separation within the various system and system protection technologies. One of the main goals our research is to enable the tighter coupling between the cyber and physical entities while addressing issues of security and trust during system inception, design, development and even deployment. This requires first understanding the cyber-physical interactions within a common language that enables the exploration of system vulnerabilities and approaches to robustness.

Research Focus

Our research focuses on the development of  CPS modeling frameworks in order to understand elements of secure (and insecure) system topologies. Our recent focus has been on the modeling of smart grid systems. In one thrust, we have identified a class of cyber-physical switching attacks via variable-structure system theory. Here, we demonstrate how an attacker can cyber-corrupt breaker control signals to destabilize a target power system component such as a synchronous generator using local state information about the power system. The work enables a better understanding of how to design smart grid topologies intrinsically robust to this form of reconfiguration attack. In another thrust, we develop a flocking-theory inspired paradigm to describe smart grid cyber-physical interactions. Such a biologically-inspired framework enables the convenient description of (discrete) cyber and (analog) physical couplings. Through this paradigm, we demonstrate active control approaches using distributed generators and storage to re-stabilize a smart grid system under various forms of cyber and physical attack.

Related Course Resources

Cyber-Physical Security of the Smart Grid

Related Publications