A Theory of Cyber Attacks: A Step Towards Analyzing MTD Systems

Moving Target Defenses (MTD) have been touted as a game changing approach to computer security that eliminates the static nature of current computer systems -- an attacker's biggest advantage. While promising, the dynamism of MTD introduces challenges related to understanding and quantifying the impact of MTD systems on security, users, and attackers. To analyze this impact, both the concepts of MTD systems and cyber attacks must be formalized. While a theory of MTD systems was proposed in [18], this paper presents a theory of cyber attacks that supports the understanding and analysis of the interaction between MTD systems and the attacks they hope to thwart. The theory defines key concepts that support precise discussion of attacker knowledge, attack types, and attack instances. The paper also presents concrete examples to show how these definitions and concepts can be used in realistic scenarios.