Can we use controllers' timing behavior for industrial security?

What is it about?

Programmable Logic Controllers or simply controllers are the brains of an industrial control system, e.g., a water treatment process or a smart grid process. Controllers could be replaced with a malicious controller if an attacker has physical access or if connected to a network, can be impersonated by an attacker. We strive to create a signature for the PLC based on hardware and software-based timing behavior representative of a particular controller. The problem we are solving is the risk-based authentication of a controller used to control industrial processes.

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Photo by Sonja Langford on Unsplash

Photo by Sonja Langford on Unsplash

Why is it important?

It is important to authenticate the controllers to ensure that the control commands come from a legitimate controller and not an attacker or modified device. Typically the controllers are resource-constrained in the sense that those have to perform the real-time operations and it might not be feasible to implement the cryptographic authentication techniques, therefore, it is important to design passive techniques that can be used outside the controllers. We used a specific property of industrial controllers that is the scan cycle to create timing-based signatures.

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