PLC and External Sensor Analytics for ICS Data Integrity

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Solution Overview

Problem

Existing methods fail to comprehensively detect anomalies in industrial control systems (ICS) due to the complexity of factory systems and noise in sensor measurements, making it difficult to ensure data integrity and detect cyber-physical attacks, especially when external sensors may not measure the same quantities as internal sensors.

Innovation Solution

The implementation of an AI-powered system that utilizes time series machine learning to analyze data from multiple sources, including PLCs and external sensors, to detect complex operation patterns over time, enabling the identification of new states and potential security incidents by comparing probabilistic representations of PLC and external sensor data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional ICS security methods (network traffic analysis, protocol inspection) are used, then detection of obvious attacks is possible, but complex cyber-physical attacks involving data manipulation remain undetected

Engineering Contradiction:
Improvedetection accuracyVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple data sources (PLC internal sensors, external sensors, network traffic data) into a unified monitoring system that cross-validates information to detect sophisticated attacks that would evade single-source detection methods

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system introduces an AI-based intermediary layer that analyzes correlations between PLC data and external sensor data, acting as a mediator to detect anomalies without requiring direct modification of the existing ICS infrastructure

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of information

If external sensors are added to monitor ICS, then additional data sources for anomaly detection are available, but integration complexity and data correlation difficulties increase

Engineering Contradiction:
Improvedata completenessVSAvoidintegration complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The system transforms external sensor data into probabilistic representations that match the format and characteristics of PLC internal sensor data, enabling direct comparison and correlation without complex integration of heterogeneous data formats

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces manual data correlation methods with AI-based probabilistic analysis that automatically identifies relationships between external sensor readings and PLC internal states, eliminating the need for manual configuration of data mappings

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If sensor noise filtering is applied to improve measurement accuracy, then data quality improves, but detection of subtle anomalies may be reduced

Engineering Contradiction:
Improvesensor accuracyVSAvoidanomaly detection capability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system applies selective filtering only to known noise patterns while preserving signal components that match expected operational variations, using AI to distinguish between benign noise and malicious anomalies based on contextual patterns

Inventive Principle:
Principle #16Partial or excessive action

4Reliability

If AI-based probabilistic analysis is implemented, then detection of complex attack patterns improves, but computational requirements and processing time increase

Engineering Contradiction:
Improveattack detection accuracyVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system pre-computes probabilistic models of normal operational patterns during system setup and training phases, enabling real-time detection to rely on comparing current readings against pre-established baselines rather than performing complex analysis on every data point

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3771951B1Using data from PLC systems and data from sensors external to the PLC systems for ensuring data integrity of industrial controllers
Publication Date: 2021.12.22 HITACHI LTD
  • EP3771951B1 patent drawingFigure 1
  • EP3771951B1 patent drawingFigure 2
  • EP3771951B1 patent drawingFigure 3

AI summary

The application relates to a method, program and apparatus executing the following steps: for a state of a factory determined from current operating conditions of the factory: receiving streaming Programmable Logic Controller (PLC) values (205) from PLCs on a network of the factory, and streaming external sensor (206) values from sensors in the factory connected externally to the network; conducting probabilistic analytics on the streaming PLC values and streaming external sensor values against historical PLC values and historical sensor values associated with the state of the factory; and for the probabilistic analytics indicative of the streaming PLC values being within expectation for the state, and the streaming external sensor values not being within expectation for the state, providing an indication of a security incident (207).