Security Modelling and Analysis of Dynamic Enterprise Networks

Dynamic networks can be characterised by many factors such as changes (e.g., vulnerability change, update of applications and services, topology changes). It is of vital importance to assess the security of such dynamic networks in order to improve the security of them. One way to assess the security is to use a graphical security model. However, the existing graphical security models (e.g., attack graphs and attack trees) have only considered static networks (i. e. the network does not change). It is also unclear how the existing cyber security metrics (e.g., attack cost, shortest attack path) change when the network configuration changes over time. To address this problem, we propose (i) to develop a novel graphical security model named Temporal-Hierarchical Attack Representation Model (T-HARM) to capture network changes and (ii) investigate the effect of network change on the existing cyber security metrics based on the proposed security model. We show how the existing security metrics change when the status of vulnerabilities changes.