NOVEL SECURE SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM ARCHITECTURE

Abstract

Supervisory Control and Data Acquisition (SCADA) systems are distributed systems commonly used in critical infrastructure to control and monitor the real-time data gathered from field devices at remote sites. SCADA systems allow human operators to interact with remote equipment through the use of a Human Machine Interface (HMI). An entire deployment of remote equipment can be observed and controlled by exchanging monitoring and control data in these systems. The use of the World Wide Web for communication purposes has led these systems to be exposed to cyberattacks. To improve the security measures of a typical SCADA system and soften this threat, a new architecture is presented. The novel system design includes Remote Terminal Units (RTUs), which are split up into two distinct components: one is a virtual control logic unit that is linked to the Master Terminal Unit (MTU) through a wide area network, while the other is a hardware control logic unit that is connected to actual field hardware (e.g., pumps, valves, sensors). All of the hardware control logic units are interconnected via a reliable local area network, thus restricting the level of direct access to the units. Under normal operation, commands from the virtual control logic unit are passed to the physical SCADA hardware through the hardware control logic unit. A trained off-the-shelf intrusion detection system (IDS) is used to detect attacks. When it trips, signaling an attack, the hardware control logic unit requests control from two other hardware logic units within the secured network that have the lowest load level. Stand-alone control from the other two units and the jeopardized node’s hardware control unit is analyzed by an arbiter algorithm and a majority-vote is then passed to the SCADA hardware. This thesis introduces the background of a typical SCADA system, its vulnerabilities, and the comprehensive analysis of the architectures proposed by different researchers. The development of a new secure SCADA system architecture will attempt to resolve the security concerns that current SCADA systems have with regard to physical attacks on the internal corporate network and when communicating over the public internet. A preliminary proof of concept of the architecture design is implemented using Raspberry Pi microcomputers, while a simulation of the system using SIEMENS Programmable Logic Controllers (PLC) within the TIA Portal software tool is developed to showcase a real-world implementation of the system architecture on industry-standard PLC.