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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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.
Perspectives
Timing channels are considered a side channel for obtaining the information helpful in launching successful attacks. We considered such a channel here as a defense mechanism. Another group also looked into this idea that is recently published, but our technique collects the same timing information on the network layer rather than inside PLCs, making it more usable. This is quite an interesting area of research and this is just the beginning, we are actively exploring this field in more depth.
Chuadhry Mujeeb Ahmed
Singapore University of Technology and Design
Read the Original
This page is a summary of: Scanning the Cycle: Timing-based Authentication on PLCs, May 2021, ACM (Association for Computing Machinery),
DOI: 10.1145/3433210.3453102.
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