Ensuring cyber network security becomes a challenging step with the increase of cyber attacks. The latter are targeting any cyber system starting from personal computers to national critical infrastructures. Consequently, the development of a proactive cyber defense technique to detect and react to cyber attacks before the damage occurrence becomes a necessity. To this end, we develop in this work a formal model to proactively ensure safety and sustainability of mission critical systems. Our proposal consists of deploying a network of observer agents to supervise and generate observation data related to attacks under execution which will be analyzed by a central defense agent. The latter will hypothetically generate a graph of potential scenarios that could be executed in the network. A scenario context will be introduced to compute a set of probabilistic measures for the proactive assessment of attack damages. Another graph decomposing the cyber network global mission into sub operations, and presenting the cyber assets ensuring mission achievement, will be presented. Such a graph will be used to study the cyber attack impact on mission accomplishment and, thus, will ensure the system sustainability by proactively reacting to cyber attacks. A case study is provided to illustrate the proposal.
Software And Hardware