We propose a model for quantification of business interruption risk in a supply chain network consisting of several firms. In order to calculate the loss distribution of supply chain disruptions for a focal firm we apply a modeling approach based on stochastic processes analysis. We present a bottom-up modeling approach to account for interdependencies among firms in the network and we reproduce the mechanisms of loss propagation. Especially the identification of firms with great impact, in case disruptions occur is very important for the risk management process. The correlation structure induced by the specific network design is incorporated and analyzed via Monte Carlo simulation. Our findings enable more informed and transparent supply chain risk management decisions.