A layered graphical model for mission attack impact analysis

Business or military missions are supported by hardware and software systems. Unanticipated cyber activities occurring in supporting systems can impact such missions. In order to quantify such impact, we describe a layered graphical model as an extension of forensic investigation. Our model has three layers: the upper layer models operational tasks that constitute the mission and their inter-dependencies. The middle layer reconstructs attack scenarios from available evidence to reconstruct their inter-relationships. In cases where not all evidence is available, the lower level reconstructs potentially missing attack steps. Using the three levels of graphs constructed in these steps, we present a method to compute the impacts of attack activities on missions. We use NIST National Vulnerability Database's (NVD)-Common Vulnerability Scoring System (CVSS) scores or forensic investigators' estimates in our impact computations. We present a case study to show the utility of our model.