Submitted:
30 June 2025
Posted:
02 July 2025
Read the latest preprint version here
Abstract
Keywords:
1. Introduction
- High-fidelity physical process simulation
- Real-time monitoring,
- Adversarial attack emulation and Hybrid anomaly detection using both physics-based and machine learning techniques.
2. Related Work
3. Core Components
3.1. Virtual SCADA Model

3.2. Attack Simulation Engine
- False Data Injection (FDI): Introduces up to ±20% sensor bias or ramps in tank level and pH readings.
- Denial of Service (DoS): Floods the PLC-HMI channel with malformed Modbus packets per second.
- Reconnaissance/Command Injection: Performs automated port scans and injects unauthorized commands, e.g., remote actuator manipulation.


3.3. Hybrid Anomaly Detector
Cyber Module:
Physical Module:
Decision Fusion:
3.4. Response Module
Alerting and Human-in-the-Loop:
Mitigation Actions:
- Stage 1: The system raises visual and audible alarms on the HMI, while logging all relevant forensic data (such as network packet captures and process sensor snapshots) for post-incident analysis.
- Stage 2: If the anomaly persists or is classified as critical, the system enforces PLC command lockdown by restricting process control to a predefined whitelist of safe operations, preventing further unauthorized manipulation.
- Stage 3: In the event of sustained or high-severity attack, the system can automatically trigger fail over to redundant backup controllers to maintain process continuity and safety.
Adaptive Learning and Concept Drift:
4. Case Study: Water Treatment Plant
4.1. Testbed Configuration
4.2. Digital Twin Implementation
4.3. Attack Scenarios
4.4. Validation Metrics and Baselines
- Snort IDS (Rule-Based): A signature-based intrusion detection engine using Modbus/TCP rules.
- Physics-Only Residual Detector: Flags physical anomalies using residual thresholds without learning or cyber analysis.
4.5. Simulation Results
4.6. Implementation Challenges and Solutions
- Physics-Guided Hybrid Detection: By fusing model-based residual analysis from a high-fidelity digital twin with cyber anomaly scores from LSTM-based learning, the framework combines the precision of process-aware monitoring with the adaptability of data-driven detection. This hybrid architecture improves detection sensitivity, especially for stealthy false data injection (FDI) attacks that may evade purely signature-based or statistical methods.
- Adversarial-Aware Attack Simulation: The framework features a configurable attack simulation engine that supports both conventional ICS threats and synthetically generated zero-day scenarios using adversarial machine learning techniques. This design provides rigorous, repeatable testing of IDS performance under a broad spectrum of threat conditions, including adaptive adversaries.
- Adaptive Decision Fusion and Threshold Optimization: A dynamic decision fusion mechanism combines cyber and physical anomaly scores with empirically tuned weights (0.3/0.7), optimized via grid search to maximize F1-score. Thresholds for detection (e.g., ) are calibrated using ROC analysis on validation data, ensuring a strong tradeoff between sensitivity and specificity.
- Edge-Cloud Operational Synergy: The system architecture supports distributed deployment: real-time anomaly scoring is handled at the edge (near PLCs and sensors), while batch retraining and forensic analysis are conducted in the cloud. This hybrid execution model enables both low-latency response and scalable analytics.
- Resilience via Concept Drift Adaptation: The detection models (LSTM and SVM) are retrained periodically using recent data and evaluated for performance drift using the Page-Hinkley test. This ensures that the DT-ID system maintains relevance in evolving operational conditions without manual recalibration.
- Integrated Replay and Visualization: The use of Unity 3D for visual twin representation and AWS IoT TwinMaker for state orchestration enables comprehensive replay of attack scenarios, operator insight, and real-time visualization bridging the gap between technical anomaly alerts and actionable engineering decisions.
5. Conclusions
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| Attack Type | Description | Parameters | Target |
|---|---|---|---|
| FDI | Sensor bias/ramp | Bias: ±20% | Level, pH |
| DoS | Modbus packet flood | /sec | PLC-HMI |
| Recon/Command | Port scan, command injection |
Scan, STOP command | PLC, Actuator |
| Attack Type | Description | Parameters | Objective |
|---|---|---|---|
| FDI | Sensor spoofing | Bias: ±20% | Trigger false tank/pH states |
| DoS | Packet flood | /sec | Disrupt PLC-HMI communication |
| Recon/Cmd | Port scan, STOP cmd |
Scan, Unauthorized cmd |
Compromise process control |
| Method | F1-score | FPR (%) | Latency (ms) |
|---|---|---|---|
| DT-ID (Ours) | 96.3 | 2.4 | 480 |
| Snort IDS | 80.5 | 4.7 | 1650 |
| Physics-Only | 89.2 | 7.8 | 510 |
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