Enhanced Modbus/TCP Security Protocol: Authentication and Authorization Functions Supported

Area of Science:

• Cybersecurity
• Industrial Control Systems Security

Background:

• Human users represent a significant vulnerability in operational technology (OT) environments, despite the adoption of Zero Trust in information technology (IT).
• Existing Modbus/TCP protocols lack robust authentication and authorization mechanisms, leaving OT systems susceptible to unauthorized access.

Purpose of the Study:

• To enhance the Modbus/TCP Security protocol by integrating authentication and authorization functions.
• To implement an access control method for industrial automation control systems (IACS) that verifies human users before granting network access.

Main Methods:

• Developed and integrated username/password-based authentication and authorization functions into the Modbus/TCP Security protocol.
• Utilized a man-in-the-middle (MITM) component to intermediate and validate client-server communications.
• Implemented the proposed security enhancements and access control method using the Node-RED programming platform.

Main Results:

• The implemented authentication and authorization functions successfully addressed the security risks posed by human users in OT deployments.
• The Node-RED platform facilitated the practical implementation and testing of the enhanced Modbus/TCP Security protocol.
• Tests confirmed the potential and applicability of the proposed access control method for securing IACS.

Conclusions:

• The enhanced Modbus/TCP Security protocol effectively mitigates unauthorized access risks in OT environments.
• Username and password-based access control, validated through MITM, is a viable security measure for IACS.
• The proposed solution offers a practical and applicable approach to improving OT security against human-related threats.