THE ADVERSARY FUNCTIONAL HIERARCHY: AN ALTERNATIVE APPROACH TO VULNERABILITY ANALYSIS OF TRANSPORTATION SYSTEMS

There are many techniques available for evaluating security systems. Such methods normally require: 1) thrsat specification, 2) target identification, 3) estimation of the capabilities of existing system elements, and 4) evaluation of the system using analytical modeling techniques to estimate system performance. Many of these techniques use computer simulations, however some systems may be difficult to model mathematically. Transportation systems, which have markedly different elements and are strongly dependent on human performance, are a good example. Because of our interest in transportation systems, we are using a non-quantitative yet logic-structured technique called the Adversary Functional Hierarchy for analyzing these systems. This structure is a hierarchy of functions or options of functions which an adversary must perform against the system to achieve his goal. In this paper, we will show why existing analysis techniques are not applicable to transportation systems, describe what an Adversary Functional Hierarchy is, apply the technique to transportation systems in a general fashion, and discuss the advantages and drawbacks of this technique.