This paper introduces a procedural method based on the fuzzy logic and set theory, which analyzes the risk of an IT-System in a facility and its surrounding area. The method analyzes the susceptibility of an electronic system with respect to intentional electromagnetic interferences and classifies the intentional electromagnetic environment (IEME). It extends the well-known statistical-based models fault tree analysis, electromagnetic topology and Bayesian networks (BN) with imprecise data, uncertainness with linguistic terms, and opinions of experts. In a final step, the critical scenarios and the elements and the location that contribute most to the risk are identified, which can be used to enhance the protection level.