GRASSMARLIN

GRASSMARLIN is a specialized cyber-physical security tool designed for the passive mapping and visualization of Industrial Control Systems (ICS) and Supervisory Control and Data Acquisition (SCADA) network topologies. Originating from the NSA, its primary purpose is to provide deep insights into the communication structures and interdependencies within critical industrial environments. By passively analyzing network traffic, GRASSMARLIN can identify and visualize the various components of an industrial network, including Programmable Logic Controllers (PLCs), Human-Machine Interfaces (HMIs), sensors, actuators, and other operational technology (OT) devices, without disrupting live operations.

This tool is exceptionally valuable for applications in advanced manufacturing, critical infrastructure protection, and industrial cybersecurity. It addresses fundamental challenges related to understanding complex and often opaque industrial networks. For instance, it can be applied to systematically define the layered architecture of an ICS, helping to enumerate attack surfaces associated with each layer, from field devices to enterprise networks. By generating detailed network maps, GRASSMARLIN aids in delineating the Purdue model for ICS and IEC 62443 zones and conduits, which are crucial for effective network segmentation and establishing trust boundaries.

Practically, GRASSMARLIN's output supports structured threat modeling for cyber-physical systems by revealing communication pathways and potential points of vulnerability. Security analysts and AI agents can leverage this visualized data to differentiate between integrity, availability, and confidentiality threats within SCADA networks, and map these to potential physical consequences in real-world operations, such as power grid management or manufacturing processes. Furthermore, it assists in classifying network interfaces by modality and identifying feasible attack primitives, which is essential for computing potential attack vectors in complex CPS environments. By providing a clear picture of network partitioning and isolation mechanisms, GRASSMARLIN enhances an organization's ability to assess their effectiveness and limitations in securing industrial processes. This foundational network intelligence is indispensable for AI-driven security analytics, anomaly detection, and proactive threat hunting in operational technology environments.