Carl Elks

Smitha Gautham, Abhilash Rajagopala, Athira Varma Jayakumar et al.

Advanced embedded system technology is one of the key driving forces behind the rapid growth of Cyber-Physical System (CPS) applications. Cyber-Physical Systems are comprised of multiple coordinating and cooperating components, which are often software intensive and interacting with each other to achieve unprecedented tasks. Such complex CPSs have multiple attack surfaces and attack vectors that we have to secure against. Towards this goal, we demonstrate a multilevel runtime safety and security monitor framework where there are monitors across the CPS for detection and isolation of attacks. We implement the runtime monitors on FPGA using a stream-based runtime verification tool called TeSSLa. We demonstrate our monitoring scheme for an Autonomous Emergency Braking (AEB) CPS system.

Georgios Bakirtzis, Brandon J. Simon, Aidan G. Collins et al.

Applying security as a lifecycle practice is becoming increasingly important to combat targeted attacks in safety-critical systems. Among others there are two significant challenges in this area: (1) the need for models that can characterize a realistic system in the absence of an implementation and (2) an automated way to associate attack vector information; that is, historical data, to such system models. We propose the cybersecurity body of knowledge (CYBOK), which takes in sufficiently characteristic models of systems and acts as a search engine for potential attack vectors. CYBOK is fundamentally an algorithmic approach to vulnerability exploration, which is a significant extension to the body of knowledge it builds upon. By using CYBOK, security analysts and system designers can work together to assess the overall security posture of systems early in their lifecycle, during major design decisions and before final product designs. Consequently, assisting in applying security earlier and throughout the systems lifecycle.

Smitha Gautham, Georgios Bakirtzis, Matthew T. Leccadito et al.

Cyber-physical systems (CPS) are composed of various embedded subsystems and require specialized software, firmware, and hardware to coordinate with the rest of the system. These multiple levels of integration expose attack surfaces which can be susceptible to attack vectors that require novel architectural methods to effectively secure against. We present a multilevel hierarchical monitor architecture cybersecurity approach applied to a flight control system. However, the principles present in this paper apply to any CPS. Additionally, the real-time nature of these monitors allow for adaptable security, meaning that they mitigate against possible classes of attacks online. This results in an appealing bolt-on solution that is independent of different system designs. Consequently, employing such monitors leads to strengthened system resiliency and dependability of safety-critical CPS.

Georgios Bakirtzis, Bryan T. Carter, Cody H. Fleming et al.

Perimeter cybersecurity, while essential, has proven insufficient against sophisticated, coordinated, and cyber-physical attacks. In contrast, mission-centric cybersecurity emphasizes finding evidence of attack impact on mission success, allowing for targeted resource allocation to mitigate vulnerabilities and protect critical assets. Mission Aware is a systems-theoretic cybersecurity analysis that identifies components which, if compromised, destabilize the overall mission. It generates evidence by finding potential attack vectors relevant to mission-linked elements and traces this evidence to mission requirements, prioritizing high-impact vulnerabilities relative to mission objectives. Mission Aware is an informational tool for system resilience by unifying cybersecurity analysis with core systems engineering goals.

Bryan Carter, Georgios Bakirtzis, Carl Elks et al.

The security of cyber-physical systems is first and foremost a safety problem, yet it is typically handled as a traditional security problem, which means that solutions are based on defending against threats and are often implemented too late. This approach neglects to take into consideration the context in which the system is intended to operate, thus system safety may be compromised. This paper presents a systems-theoretic analysis approach that combines stakeholder perspectives with a modified version of Systems-Theoretic Accident Model and Process (STAMP) that allows decision-makers to strategically enhance the safety, resilience, and security of a cyber-physical system against potential threats. This methodology allows the capture of vital mission-specific information in a model, which then allows analysts to identify and mitigate vulnerabilities in the locations most critical to mission success. We present an overview of the general approach followed by a real example using an unmanned aerial vehicle conducting a reconnaissance mission.

Georgios Bakirtzis, Bryan T. Carter, Carl R. Elks et al.

Evaluating the security of cyber-physical systems throughout their life cycle is necessary to assure that they can be deployed and operated in safety-critical applications, such as infrastructure, military, and transportation. Most safety and security decisions that can have major effects on mitigation strategy options after deployment are made early in the system's life cycle. To allow for a vulnerability analysis before deployment, a sufficient well-formed model has to be constructed. To construct such a model we produce a taxonomy of attributes; that is, a generalized schema for system attributes. This schema captures the necessary specificity that characterizes a possible real system and can also map to the attack vector space associated with the model's attributes. In this way, we can match possible attack vectors and provide architectural mitigation at the design phase. We present a model of a flight control system encoded in the Systems Modeling Language, commonly known as SysML, but also show agnosticism with respect to the modeling language or tool used.