ISA ISA-IEC-62443 - ISA/IEC 62443 Cybersecurity Fundamentals Specialist

ISA/IEC 62443-4-1 provides a framework for secure product development lifecycle (SDL). One of its primary goals is to ensure that security practices are integrated consistently and systematically throughout the product's development process.

“The objective of this part is to define a secure development lifecycle process that results in a consistent and repeatable approach to building secure products.”

— ISA/IEC 62443-4-1:2018, Clause 1 – Scope

While all listed items may contribute to security, the core intent of Part 4-1 is to ensure an aligned, structured development process.

Modbus TCP is a widely used protocol in industrial control systems, enabling communication between devices such as PLCs and SCADA systems over Ethernet networks. It is an adaptation of the classic Modbus protocol to TCP/IP networks and is explicitly referenced in ISA/IEC 62443 documentation as a common protocol for IACS communications. FTP, HTTP, and SMTP are general IT protocols and not primarily associated with industrial control communications.

A Host-based Intrusion Detection System (IDS) is a device or software application used to monitor and analyze the internals of a computing system (host) for malicious activity or policy violations. Unlike routers, switches, or even firewalls, which focus on network traffic or connectivity, a host-based IDS operates on individual machines to detect unauthorized activity or changes.

In the Assess phase of the IACS Cybersecurity Lifecycle (as defined in ISA/IEC 62443-2-1 and 62443-3-2), the main objective is to identify assets, analyze risks, and assign a Target Security Level (SL-T) for each zone or conduit. This sets the foundation for design and implementation decisions. Achieving or verifying the SL-A (Achieved Security Level) occurs later in the lifecycle, after implementation.

An asset model is a structured framework used to catalog, categorize, and manage assets in an industrial control environment. It allows organizations to track the status, relationships, and criticality of equipment, supporting effective risk management and security planning.

“Asset models define the components of the system and their interrelationships to support activities such as risk analysis, security monitoring, and maintenance.”

— ISA/IEC 62443-1-1:2007, Clause 4.3 – Asset and Component Modeling

In contrast:

Conduits represent communication paths between zones

Security zones group assets by security requirements

Reference architectures are templates for system design—not for tracking assets

Patches are software updates that fix bugs, vulnerabilities, or improve performance or functionality. Patches are important for maintaining the security and reliability of an IACS environment, but they also pose some challenges and risks. Applying patches in an IACS environment is not as simple as in an IT environment, because patches may affect the availability, integrity, or safety of the IACS. Therefore, patches should not be applied blindly or automatically, but based on the organization’s risk assessment. The risk assessment should consider the following factors: 1

The severity and likelihood of the vulnerability that the patch addresses

The impact of the patch on the IACS functionality and performance

The compatibility of the patch with the IACS components and configuration

The availability of a backup or recovery plan in case the patch fails or causes problems

The testing and validation of the patch before applying it to the production system

The communication and coordination with the stakeholders involved in the patching process

The documentation and auditing of the patching activities and results References: ISA TR62443-2-3 - Security for industrial automation and control systems, Part 2-3: Patch management in the IACS environment

According to ISA/IEC 62443-1-1:2007 (Terminology, Concepts, and Models), the functional levels of the Industrial Automation and Control System (IACS) are derived from the Purdue Enterprise Reference Architecture (PERA). These levels are defined as follows:

Level

Function

Description

Level 0

Process

The actual physical process, including sensors and actuators.

Level 1

Basic Control

Devices responsible for direct control, such as PLCs and RTUs.

Level 2

Area Supervisory Control

Supervisory systems such as HMIs and SCADA, responsible for monitoring/control.

Level 3

Site Manufacturing Operations Management

Operations management systems such as MES, production scheduling, and workflow.

Level 4

Business Planning and Logistics

Enterprise-level systems such as ERP, supply chain, and logistics.

Analysis of Each Option:

Option A: Level 1: Supervisory Control

Incorrect. Level 1 is defined as Basic Control, not Supervisory Control. Supervisory functions appear at Level 2.

Option B: Level 2: Quality Control

Incorrect. Level 2 is defined as Area Supervisory Control, not Quality Control.

Option C: Level 3: Operations Management

Correct. Level 3 is specifically identified as Operations Management, which includes manufacturing execution and scheduling functions.

Option D: Level 4: Process

Incorrect. Level 4 corresponds to Business Planning and Logistics. The Process is represented at Level 0.

 According to the ISA/IEC 62443-2-4 standard, a training and security awareness program should include all personnel who have access to the industrial automation and control system (IACS) or who are involved in its operation, maintenance, or management. This includes vendors and suppliers, employees, temporary staff, contractors, and visitors. The purpose of the program is to ensure that all personnel are aware of the security risks and policies related to the IACS, and that they have the necessary skills and knowledge to perform their roles in a secure manner. The program should also cover the roles and responsibilities of different personnel, the reporting procedures for security incidents, and the best practices for security hygiene. References:

ISA/IEC 62443-2-4:2015 - Security for industrial automation and control systems - Part 2-4: Security program requirements for IACS service providers1

ISA/IEC 62443 Cybersecurity Fundamentals Specialist Training Course2

 The risk analysis category of an IACS consists of two elements: business rationale and risk identification and classification1. Business rationale is the process of defining the scope, objectives, and criteria for the risk analysis, as well as the roles and responsibilities of the stakeholders involved. Risk identification and classification is the process of identifying the assets, threats, vulnerabilities, and consequences of a cyberattack on the IACS, and assigning a risk level to each scenario based on the likelihood and impact of the attack1. These elements are essential for establishing a baseline of the current risk posture of the IACS and determining the appropriate risk treatment measures to reduce the risk to an acceptable level. References: 1: ISA/IEC 62443-3-2:2020, Security for industrial automation and control systems - Part 3-2: Security risk assessment for system design, International Society of Automation, Research Triangle Park, NC, USA, 2020.

ISA/IEC 62443 defines zones and conduits as a core architectural concept for managing cybersecurity risk in IACS environments. During risk assessment, zones must be clearly separated based on risk, function, and criticality, not convenience.

Step 1: Definition of zones in ISA/IEC 62443

A zone is a grouping of assets that share similar security requirements and risk profiles. Business systems, safety-critical control systems, and wireless systems inherently have different threat exposures and consequences of compromise.

Step 2: Risk-based separation principle

ISA/IEC 62443-3-2 requires that risk assessments identify differences in impact and threat likelihood. Safety-critical zones typically require higher Security Levels due to potential impacts on human safety and the environment. Business zones, by contrast, tolerate different risk levels.

Step 3: Purpose of separation

Clear separation ensures that security requirements can be applied appropriately to each zone. It also limits the propagation of attacks from lower-criticality zones (such as business or wireless networks) into higher-criticality zones.

Step 4: Why other options are incorrect

Combining all zones ignores risk differentiation and violates the core zone concept.

Ignoring physical location is incorrect; while zones are logical, physical access and connectivity still matter in risk assessment.

Treating temporary connections as permanent safety assets distorts the risk model and security requirements.

Step 5: Outcome of proper zone management

By establishing clear separation based on criticality, asset owners can correctly assign Security Levels, define conduits, and apply appropriate technical and procedural controls.

Therefore, ISA/IEC 62443 requires clear separation between zones based on criticality during risk assessment.