security analysis using Fault Trees (FT)

There are many previous work on using fault trees in reliability and availability modeling. Very few is on safety modeling and security modeling of cyber physical system. Fault trees are more powerful than reliability block diagrams (RBD) with shared nodes.

One potential idea is that I could transform the system model into fault trees and then compared them. Fault trees could be used to validate the system model. Fault trees are well suited for this purpose because they are specifically intended to capture the relationship between component failure and system faults, with an assumption that all basic events be statistically independent.

But there is a key problem here: What's your research object? At least there should be a real system or existing model you can investigate into, some people have there physical system like UAV, while some other people may have their SCADA simulation system. What do you have? Simulation model of NCS? Maybe.

Combinatorial models

--Reliability Block Diagrams: (RBD) map the operational dependency of a system on its components and not the physical structure of the system, including blocks, edges, and dummy nodes. Some software packages have been developed to support construction and solution of RBD models and now it is frequently used in reliability and availability modeling. We have yet to see an application of RBDs in security modeling, but needs to create a compositional theory of security first.

Here is a brief introduction of RBDs: http://www.reliabilityeducation.com/rbd.pdf

It defines logical interaction of failures within a system that are required to sustain system operation. Once the blocks are configured properly and block data is provided, the failure rate, MTBF(mean time between failures), reliability, and availability of the system can be calculated. When it comes to security field, we need to care confidentiality and integrity, using the same method. It is also a good idea if we could use RBD to do security modeling and then quantitatively measure the security of system in order to help IT manager to manage the trade-off between functionality and security.