Approaches for modeling a risk of security breaches to a network. Agents gather, from multiple sources across the network, analysis data that identifies observed characteristics of habitable nodes and opaque nodes. Using the analysis data a multi-layer risk model for the network is generated that comprises a first layer that models an inherent risk of security breaches to assets of the network based on the observed characteristics. The model also comprises a second layer that models a present state of the inherent risk to the assets caused by global and temporal events. The model also comprises a third layer that models a change to the risk of security breaches in response to potential mitigative actions. The model may be used to understand how risk of a security breach is distributed and interdependent upon the nodes of the network so as to allow the most valuable preventive measures to be taken.