Free ISA ISA-IEC-62443 Practice Exam with Questions & Answers | Set: 5

The ISA/IEC 62443 standards series was originally developed by the International Society of Automation (ISA) and then adopted and published by the International Electrotechnical Commission (IEC) as the IEC 62443 series. The IEC is the primary international body responsible for the ongoing development, maintenance, and publication of these standards, which are recognized globally for IACS cybersecurity. ANSI is a US standards body, NIST is responsible for US federal cybersecurity frameworks, and ETSI develops telecommunications standards for Europe, but IEC is the correct answer here.

The primary goal of the NIST Cybersecurity Framework (CSF) is to help organizations enhance the security and resilience of critical infrastructure and reduce cybersecurity risks through a structured, risk-based approach.

“The Framework provides a policy framework of computer security guidance for how private sector organizations in the United States can assess and improve their ability to prevent, detect, and respond to cyber attacks. It is intended to enhance the resilience of critical infrastructure.”

— NIST CSF v1.1, Section 1.0 – Overview

The NIST CSF does not create new standards or certify organizations — it references existing standards and guides implementation in a flexible and sector-neutral way.

OPC Unified Architecture (OPC UA) introduces a browsable namespace that supports hierarchical organization of data including folders, classes, methods, and object types. This is critical for structured access to real-time and historical data across heterogeneous control systems.

“OPC UA provides a flexible, secure, and platform-independent mechanism for exchanging information. Its browsable namespace allows structured navigation of nodes, types, and attributes in a hierarchical format.”

— OPC UA Specification, Part 3 – Address Space Model

This is a key improvement over OPC Classic, which was tightly coupled to DCOM and lacked standardized structures across systems.

For U.S. federal agencies, mandatory cybersecurity requirements under law are established through Federal Information Processing Standards (FIPS). FIPS are issued by the U.S. government and are legally enforceable for federal agencies and contractors when specified by statute or regulation. This legal enforceability distinguishes FIPS from voluntary standards and frameworks.

Step 1: Understand the legal nature of FIPS

FIPS are developed under U.S. law to define minimum security requirements for federal information systems. When a federal agency operates or procures information systems, compliance with applicable FIPS is mandatory. This makes FIPS a legal obligation rather than a best-practice recommendation.

Step 2: Differentiate standards vs regulations

ISA/IEC 62443 is an international consensus-based standard intended primarily for industrial automation and control systems. While widely adopted and referenced by regulators, it is not legally mandatory unless explicitly incorporated into law or contracts. Therefore, it does not satisfy the requirement “under law” by itself.

Step 3: Eliminate incorrect options

The EU Cyber Resilience Act applies to products placed on the European Union market and has no jurisdiction over U.S. federal agencies.

NIST SP 800-171 provides requirements for protecting Controlled Unclassified Information (CUI) in non-federal systems, but it becomes mandatory only through contractual flow-downs, not directly as federal law.

Step 4: Align with ISA/IEC 62443 perspective

ISA/IEC 62443 acknowledges that regulatory and legal obligations override voluntary standards. Asset owners must comply with applicable laws first, then apply ISA/IEC 62443 controls to meet industrial cybersecurity objectives.

Thus, for a U.S. federal agency facing mandatory cybersecurity requirements under law, NIST FIPS is the correct answer.

Packet filter firewalls, as defined by ISA/IEC 62443 standards on cybersecurity, primarily examine the source, destination, and ports in the header of each packet. This type of firewall does not inspect the packet content deeply (such as its structure or sequence) or maintain awareness of the relationships between packets in a session. Instead, it operates at a more superficial level, filtering packets based solely on IP addresses and TCP/UDP ports. This approach allows packet filter firewalls to quickly process and either accept or block packets based on these predefined criteria without delving into the complexities of session management or the content of the packets up to the application layer.

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.

“Defense in Depth” is a foundational principle in ISA/IEC 62443, defined as:

“The application of multiple security countermeasures in a layered (stepwise) fashion to protect assets.”

(ISA/IEC 62443-1-1, Clause 3.2.65)

The objective is to reduce the probability that a single point of failure or vulnerability can be exploited to compromise the system. Layers may include physical security, network segmentation, authentication, intrusion detection, and endpoint protection.

From ISA/IEC 62443-3-3:

“Defense in depth should be employed to provide redundancy in security mechanisms. Each layer increases the security of the system and mitigates different types of threats.”

Incorrect Options:

A and B – Misinterpret the concept as technical complexity, rather than layered protection.

C – Refers to physical spacing, not a cybersecurity strategy.

ISA/IEC 62443-2-1 explicitly requires that the IACS Security Program be integrated into the organization’s overall management structure.

Step 1: Integration principle

The standard states that IACS security must align with business processes, governance, and enterprise security management rather than operate in isolation.

Step 2: Alignment with ISMS

Where an Information Security Management System (ISMS) exists, the IACS SP should be embedded within it to ensure consistent risk management, policy enforcement, and continuous improvement.

Step 3: Why other options are incorrect

Standalone security programs create silos. Full outsourcing violates asset owner accountability. Purely technical approaches ignore human and process factors.

Step 4: Operational outcome

Embedding the SP ensures sustainability, consistency, and executive oversight.

Therefore, the correct answer is by embedding it into organizational processes and the ISMS.

The best practice for detection-in-depth according to ISA/IEC 62443 involves layering different types of security controls that operate effectively under multiple scenarios and across various zones within an environment. IDS (Intrusion Detection Systems) sensors deployed across multiple zones within a production environment exemplify this strategy. By positioning sensors in various strategic locations, organizations can monitor for anomalous activities and potential threats throughout their network, thus enhancing their ability to detect and respond to incidents before they escalate. This deployment aligns with the ISA/IEC 62443 focus on comprehensive coverage and redundancy in cybersecurity mechanisms, contrasting with relying solely on perimeter defenses or single-point security solutions.

Even the most modern and sophisticated safety systems can be defeated by an attacker. This statement is validated by the discovery of malware specifically targeting safety instrumented systems (SIS), such as the "Triton/Trisis" malware that compromised the SIS of a petrochemical plant. Safety systems, while designed as independent protection layers, are not immune to cybersecurity vulnerabilities and require specific countermeasures. Integration, such as using Modbus TCP, does not inherently reduce risk to a tolerable level without additional controls.