Information and Communication Technology (ICT) systems are now ubiquitous in all aspects of our society. With an ability to create ICT incident effects via cyberspace, criminals can steal information or extort money, terrorists can disrupt society or cause loss of life, and the effectiveness of a military can be degraded. These threats have caused an imperative to maximize a system’s cyber security resilience. Protecting systems that rely on ICT from cyber-attacks or reducing the impacts that cyber incidents cause is a topic of major importance. In this paper, we describe an approach to minimizing cybersecurity risks called Cyber Security Game (CSG), where CSG can be viewed as a form of model-based system security engineering. CSG is a method and supporting software that quantitatively identifies mission outcome focused cybersecurity risks and uses this metric to determine the optimal employment of security methods to use for any given investment level. CSG maximizes a system’s ability to operate in today’s contested cyber environment by minimizing its mission risk. The risk score is calculated by using a cyber mission impact assessment (CMIA) model to compute the consequences of cyber incidents, and by applying a threat model to a system topology model and defender model to estimate how likely attacks are to succeed. CSG takes into account the widespread interconnectedness of cyber systems, where defenders must defend all multi-step attack paths and an attacker only needs one to succeed. It employs a game theoretic solution using a game formulation that identifies defense strategies to minimize the maximum cyber risk (MiniMax), employing the defense methods defined in the defender model. This paper describes the approach and the models that CSG uses.
cybersecurity, game theory, return on investment, risk assessment, risk management
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