Supervisory Control and Data Acquisition (SCADA) systems are a type of Industrial Con- trol System (ICS) that both monitor and control the critical infrastructure that delivers man- ufactured goods, water, and energy. These systems are responsible for supervising everything from natural gas valves to electric substations. For the past half century, SCADA and ICS networks have been proprietary, closed systems, entirely contained within a private network. Their security was derived from air gap networking, physically isolating these systems from the Internet. However, system operators are increasingly opting to connect their control systems to Internet or corporate intranet networks in order to substantially reduce operating costs and improve reporting capabilities. This architecture change has given rise to a new and poorly understood class of risk.

In this work, we examine how a security concept known as Active Device Authentication can be applied to the SCADA system threat model. As our contribution, we develop a software tool known as Gatekeeper that wraps Active Device Authentication capabilities around exist- ing, weaker authentication mechanisms present in off-the-shelf HMI software written in Java. This work aims to provide the reader with a stronger understanding of the concept of Active Device Authentication, and how it can be deployed into legacy, proprietary, or mission-critical environments to enable additional security controls without risk of impacting the underlying systems’ reliability.