ISA/IEC-62443/ISA-99 Based Control System Cybersecurity Detailed Risk Assessment
The move by most, if not all, DCS vendors towards “open systems” and the resulting incorporation of off-the- shelf technologies represented a significant shift in control system design. System integration became easier, product development by manufacturers was accelerated, and training was simplified as it leveraged common tools and concepts. While the benefits have been tremendous, at the same time, open technology has now allowed control systems to be exposed by frequent and significant security vulnerabilities, putting production, assets, and human safety at risk. Gone are the days of proprietary operating systems and communication busses, isolated systems, and inherently secure processing environments.
A detailed cyber risk assessment will rigorously evaluate the Industrial Automation Control System (IACS) and ensure the design and procedures are capable of satisfying the corporate risk criteria. To do this, identification of the potential threat vectors and associated countermeasures is essential.
A Control System Cybersecurity Detailed Risk Assessment (CDRA)
- Using methodology similar to a HAZOP, the Cyber Detailed Risk Assessment evaluates cyber nodes that represent the cyber assets that are part of the zone and conduit design.
- The primary focus is with the control and safety systems, however, the entire plant network including all internet and wireless access points, including 3rd party connections, networks, and devices need to be evaluated as they can be • pathways to compromise the IACS.
- The Methodology evaluates whether current risk reductions are sufficient to satisfy corporate risk criteria, or if further mitigations need to be implemented to achieved further level of risk reduction via the defense in depth strategy.
- Enables the company to focus resources and efforts on areas that need higher security applied, and acknowledging areas that may not.
The Process
- Using the critical assets identified in the High Level Risk Assessment, assets are evaluated as to likelihood of attack, potential consequence severity, vulnerability and non-cyber susceptible protections.
- Using the results of a Cybersecurity Vulnerability Assessment, Individual devices are examined to identify if an identified vulnerability was exploited, what would be the consequence, and if that exploit can propagate to other devices.
- Identifies steps which have previously been done to protect the device and therefore the IACS, and if any further mitigations are necessary.
- Formally document the results in an assessment report, likelihood, consequences, unmitigated risk and then residual risk are all documented within the spreadsheets.
Benefits
- Provides management with solid understanding of current criticality, unmitigated and residual risk.
- Identifies hazards which have been protected through non-cyber vulnerable means.
- Provides definitive direction to management as to where resources should be focused and applied.
- Short Duration – most systems can be assessed in about a week - and minimally invasive to personnel, and non invasive to the PCN itself.
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