AWWA WSC70053

This paper is based upon experiences from security assessments of supervisory control and data acquisition (SCADA) systems, including assessment performed at one of Sweden's larger water facilities. The paper highlights findings and examines state-of-the-art control system models. These models are commonly used in the water sector and provide an abstract representation of the system architecture. These kinds of models are indeed a powerful tool for the facility owners and other stakeholders that need to understand the system configuration. However, these abstract representations are seldom aligned with the reality. This paper takes a closer look at some abstract representations and reveals some cases where they actually make the world look "nicer" than it is from a security perspective. It looks nicer merely because the deficient abstract representations don't really show system weaknesses that could have critical consequences. The overall consequence is that the operator of a water facility can be deceived to believe that the security level is far better than it is in reality, simply because details of the system are not scrutinized enough in his models. Includes 22 references, figures.