OWA trees and their role in security modeling using attack trees

We introduce the idea of an OWA node as an extension of the “and/or” node and use them to generalize “and/or” trees to OWA trees. We provide a semantics for an OWA node. Specifically while an “or” node requires only one of the children to be satisfied and an “and” node requires “all” the children be satisfied the OWA node allows us to model situations in which there is some probabilistic uncertainty in the number of children that need be satisfied. We then use these OWA nodes in the security related problem of constructing attack trees. Techniques for the evaluation of an OWA attack tree for the overall probability of success and cost of an attack are provided. A method is provided for describing different types of attackers.