Design and Implementation of a Secure Modbus Protocol

The interconnectivity of modern and legacy supervisory control and data acquisition (SCADA) systems with corporate networks and the Internet has significantly increased the threats to critical infrastructure assets. Meanwhile, traditional IT security solutions such as firewalls, intrusion detection systems and antivirus software are relatively ineffective against attacks that specifically target vulnerabilities in SCADA protocols. This paper describes a secure version of the Modbus SCADA protocol that incorporates integrity, authentication, non-repudiation and anti-replay mechanisms. Experimental results using a power plant testbed indicate that the augmented protocol provides good security functionality without significant overhead.