Using CP-nets as a guide for countermeasure selection

In this paper we present a qualitative approach for the selec- tion of security countermeasures able to protect an IT system from attacks. For this purpose, we model security sce- narios by using defense trees (an extension of attack trees) and preferences over countermeasure using Conditional Pref- erence networks (CP-nets for short). In particular, we in- troduce two different methods for the composition of pref- erences: the and-composition and the or-composition. The first one is used to determine a preference order in the selec- tion of countermeasures able to mitigate the risks produced by conjunct attacks. The second one is used to determine a preference order over sets of countermeasures able to miti- gate the risks produced by alternative attacks.