On the Impact of Uncertainty on Quantitative Security Risk Assessment

Kurzfassung

The importance of (physical) security nowadays gets more and more acknowledged in society as well as in the scientific community. In the light of increasing terrorist threat levels, assessments of the security of critical infrastructures are conducted in practice and researchers propose new approaches. While practical security risk assessments (SRA) use mostly qualitative methods, most of the lately proposed approaches are based on quantitative metrics. Rare evidence of actual attacks qualitative and quantitative approaches suffers the fundamental problem of inherent uncertainties regarding occurring threats and capabilities of security measures. This paper focuses on the impact of considering uncertainties in quantitative SRA, especially regarding the robustness of the system against resulting input parameter variance. The impact is analyzed by applying quantitative vulnerability assessment introduced by Lichte and Wolf (2017) as part of the SRA process to an airport structure. Two differing configuration are initially assessed. Additionally, an adapted Variance Based Sensitivity Analysis for first and total order sensitivities is conducted. Finally, a hybrid configuration based on the findings of the prior steps is realized in the sixth step. The results substantiate the assumption regarding the differing influence of the models input parameters. Hence, the approach of Factor Fixing can help in systematically identifying the most influencing factors of the uncertainty considering vulnerability model.