Physical Device for security analysis of power systems

It is a master level thesis

1. Web Server (http, ssh) Router Host 0 Adversary Host 1 Internal User External Firewall Internal Firewall File Server (ftp, ssh) Database Server(ssh)

2. Gateway 1 Redundant Gateway Gateway 2 Server 1 Server 2 Network Switch 3 Network Switch 1 Network Switch 2 Printer HMI Router Ethernet 1 Ethernet 2 Ethernet 3 Ethernet 4 Ethernet 5 BCU 1 Relay 1 BCU 2 Relay 2 BCU 3 Relay 3 BCU 4 Relay 4 BCU 5 Relay 5

3.   We can expand it by considering each possible combination of values for the parent nodes. Let's say X has n parent nodes, denoted by Y1,Y2,…,Yn​ . The summation expands to: P ( X )= P ( X ∣ Y 1​, Y 2​,…, Yn ​)× P ( Y 1​, Y 2​,…, Yn ​)+ P ( X ∣¬ Y 1​, Y 2​,…, Yn ​)× P (¬ Y 1​, Y 2​,…, Yn ​)+ P ( X ∣ Y 1​,¬ Y 2​, Y 3​,…, Yn ​)× P ( Y 1​,¬ Y 2​, Y 3​,…, Yn ​)+……..+ P ( X ∣¬ Y 1​,¬ Y 2​,…,¬ Yn ​)× P (¬ Y 1​,¬ Y 2​,…,¬ Yn ​) Where: P ( X ∣ Y 1​, Y 2​,…, Yn ​) is the conditional probability of X given its parents Y 1​, Y 2​,…, Yn ​ . P ( Y 1​, Y 2​,…, Yn ​) is the joint probability of the parent nodes taking on specific values. The expansion continues for all possible combinations of compromised( Y 1) or uncompromised (¬ Y 1 ) of values for the parent nodes. Mathematically, if the parent nodes are independent of each other, you simply multiply the probabilities of each individual parent node: P ( Y 1​, Y 2​,…, Yn ​) = P ( Y 1​) × P ( Y 2​) ×……..…× P ( Yn ​) Unconditional Probability Calculation

4. = 0+0.3*1 = 0.3 = 0+1*1 = 1 = 0 + 0.78 * 0 * 0.3 + 0.98 * 1 * 0.7 + 0.9956 * 1 *0.3 = 0.98468   Unconditional Probability Calculation