Quantitative analysis of information security interdependency between industrial sectors

This paper employs Input-Output analysis to quantitatively analyze cross-sectoral security interdependency in terms of economic activity. Previous studies using the Inoperability Input-Output Model (IIM) have demonstrated the impact of cross-sectoral security incidents from the viewpoint of interdependency. However, the two primary limitations of these studies are that (1) they do not consider each sector´s features in terms of information technology (IT) and information security (IS), and (2) they focus on the damage caused by IS incidents to sectors and do not consider the level of security interdependency itself. The author proposes a practical methodology to measure sectoral IS interdependency by introducing forward linkage and backward linkage analyses into an IIM. The methodology assesses the dependency of each sector with respect to IT and the level of IS measures. Furthermore, the paper applies the methodology to recent statistical economic data of Japanese industrial sectors and illustrates the implications of cross-sectoral security interdependency.