PLC Module Isolation With Rule-Based Data Mediation
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Solution Overview
Problem
Cyberattacks on automated control systems (ACS) are prevalent due to vulnerabilities in programmable logic controllers (PLCs), particularly in their execution systems, which are either inflexible and deterministic or flexible but insecure, lacking effective information security measures.
Innovation Solution
The PLC execution system is divided into modules, with a security module monitoring interactions and isolating segments of code and data, ensuring that critical components are segregated from vulnerable ones, and all interactions are routed through the security module to enforce compliance with predefined rules for secure data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PLC execution system uses monolithic or multicomponent program executed in virtual address space, then functional flexibility is improved, but security is worsened because any compromised functional component compromises the entire PLC execution system
Solution Approach 1:
The PLC execution system is divided into multiple isolated modules, each running in its own address space. Critical functional components are segmented into separate modules that cannot compromise the entire system if breached. The system includes: a PLC execution system with multiple modules, each with its own address space; a security module that monitors interactions between modules; and isolation mechanisms that prevent lateral movement of attacks.
2Reliability
If PLC design executes strictly deterministic problem without execution systems, then security is improved by ruling out flexibility, but adaptability is worsened as switching between production kinds requires significant time and labor
Solution Approach 1:
The system segments deterministic control functions into isolated modules that maintain security while enabling flexibility. Each module can be independently configured and executed, allowing production switching without compromising system security. The modular architecture permits reconfiguration of production parameters while maintaining the security boundaries established by the segmentation principle.
3Adaptability or versatility
If PLC uses execution systems with maximum flexibility, then adaptability is improved, but information security is worsened as security measures are totally ignored
Solution Approach 1:
A security module acts as an intermediary between PLC execution modules and the operating system, monitoring and controlling all interactions. This intermediary enforces security policies while permitting flexible module execution. The security module intercepts and validates communication between modules and OS resources, blocking malicious interactions while allowing legitimate flexible operations.
4Reliability
If functional components are isolated into separate modules with monitored interactions, then security is improved by preventing compromise propagation, but device complexity is worsened due to additional security module and modified data exchange interfaces
Solution Approach 1:
The system uses segmentation to divide the PLC execution environment into isolated modules, each with defined security boundaries. While this increases architectural complexity, it fundamentally improves security by preventing attack propagation. The segmentation principle organizes complexity into manageable, isolated units rather than a monolithic structure.
Solution Approach 2:
The security module serves as a centralized intermediary that manages security policies for all module interactions. This approach consolidates security logic in a single component rather than distributing complex security checks across all module interfaces, thereby managing overall system complexity while maintaining strong security boundaries.
Data Source
AI summary
Disclosed systems and methods for enabling data to be transmitted between program modules based on compliance with rules, the method comprising: monitoring, by a security module executable by a processor, an interaction between a first program module and a second program module to determine whether the interaction complies with at least one rule, wherein the first program module is a source of data being exchanged with the second program module which is a recipient of the data, when the interaction does not comply with the at least one rule, modifying the data being exchanged between the source and the recipient of the data, and when the interaction complies with the at least one rule, allowing the data to be transmitted to the recipient.