Pass the ISA Cybersecurity ISA-IEC-62443 Questions and answers with CertsForce

Security zones are logical groupings of assets that share common security requirements based on factors such as criticality, consequence, vulnerability, and threat. Security zones are used to apply the principle of defense in depth, which means creating multiple layers of protection to prevent or mitigate cyberattacks. By creating security zones, asset owners can isolate the most critical or sensitive assets from the less critical or sensitive ones, and apply different levels of security controls to each zone according to the risk assessment. Security zones are not necessarily aligned with physical network segments, as assets within the same network may have different security requirements. For example, a network segment may contain both a safety instrumented system (SIS) and a human-machine interface (HMI), but the SIS has a higher security requirement than the HMI. Therefore, the SIS and the HMI should be in different security zones, even if they are in the same network segment. Similarly, assets within the same logical communication network may not have the same security requirements, and therefore should not be in the same security zone. For example, a logical communication network may span across multiple physical locations, such as a plant and a corporate office, but the assets in the plant may have higher security requirements than the assets in the office. Therefore, the assets in the plant and the office should be in different security zones, even if they are in the same logical communication network. Finally, all components in a large or complex system should not be in the same security zone, as this would create a single point of failure and expose the entire system to potential cyberattacks. Instead, the components should be divided into smaller and simpler security zones, based on their security requirements, and the communication between the zones should be controlled by conduits. Conduits are logical or physical connections between security zones that allow data flow and access control. Conduits should be designed to minimize the attack surface and the potential impact of cyberattacks, by applying security controls such as firewalls, encryption, authentication, and authorization. References:

How to Define Zones and Conduits1

Securing industrial networks: What is ISA/IEC 62443?2

ISA/IEC 62443 Series of Standards3

In ANSI/ISA-99.00.01:2007, which is part of the ISA/IEC 62443 standards, electronic security encompasses both the technical and human aspects of cybersecurity within industrial automated and control systems (IACS). Option B correctly highlights components such as computers, networks, operating systems, applications, and other programmable configurable components which are intrinsic to the system's electronic security framework. Option C is also correct as it includes the personnel, policies, and procedures which play a crucial role in securing these systems. This emphasizes that security is not only about the technological solutions but also about managing human elements and organizational processes effectively.

ISA/IEC 62443 Cybersecurity Fundamentals References:

ISA/IEC 62443 standards focus on the holistic nature of security which is clearly supported by including both the technological (Option B) and human elements (Option C) in the definition of electronic security.

The NIST Cybersecurity Framework (CSF) is explicitly designed to be flexible, voluntary, and sector-agnostic, making it suitable for diverse environments — including multinational corporations operating in multiple regulatory jurisdictions.

“The Framework is intended to be used by organizations of all sizes, across all sectors and countries. It is technology-neutral and allows for continuous improvement through its tiered implementation and feedback loop.”

— NIST Cybersecurity Framework v1.1, Section 1.2 – Framework Overview

This flexibility allows organizations to tailor their implementation to fit their risk appetite, regulatory requirements, and industry practices.

 According to the ISA/IEC 62443 Cybersecurity Fundamentals Specialist resources, patches are software updates that fix bugs, vulnerabilities, or improve performance of a system. Patches are classified into three categories based on their urgency and impact: low, medium, and high. Low priority patches are those that have minimal or no impact on the system functionality or security, and can be applied at the next scheduled maintenance. Medium priority patches are those that have moderate impact on the system functionality or security, and should be applied within a reasonable time frame, such as three months. High priority patches are those that have significant or critical impact on the system functionality or security, and should be applied as soon as possible, preferably at the first unscheduled outage. Applying patches in a timely manner is a best practice for maintaining the security and reliability of an industrial automation and control system (IACS). References:

ISA/IEC 62443 Cybersecurity Fundamentals Specialist Study Guide, Section 4.3.2, Patch Management

ISA/IEC 62443-2-1:2009, Security for industrial automation and control systems - Part 2-1: Establishing an industrial automation and control systems security program, Clause 5.3.2.2, Patch management

ISA/IEC 62443-3-3:2013, Security for industrial automation and control systems - Part 3-3: System security requirements and security levels, Clause 4.3.3.6.2, Patch management

ISA/IEC 62443 recognizes that some industries require sector-specific interpretations of cybersecurity controls. For the energy sector, ISO/IEC 27019 fills this role.

Step 1: Scope of ISO/IEC 27019

ISO/IEC 27019 provides information security controls specifically tailored for energy utility process control systems, including power generation, transmission, and distribution.

Step 2: Alignment with ISA/IEC 62443

ISO/IEC 27019 complements ISA/IEC 62443 by adapting ISMS-based controls to OT and ICS environments, addressing availability, safety, and real-time constraints.

Step 3: Why other options are less suitable

ISO/IEC 27001 is general-purpose and not ICS-specific. NIST SP 800-53 is broad and IT-centric. IEC PAS documents are not comprehensive sector standards.

Therefore, ISO/IEC 27019 is the most appropriate choice.

The ISA/IEC 62443-2-1 standard introduces Security Program Maturity Levels, which help assess how well an organization has integrated security into its industrial operations. Level 1 is the "Initial" stage where processes are ad-hoc, undocumented, and vary across the organization — precisely the case described in the question.

“Maturity Level 1 (Initial) — Processes are ad hoc and undocumented. There is no consistency in how security is implemented across the organization or teams. Security activities are performed inconsistently, typically in response to incidents.”

— ISA/IEC 62443-2-1:2010, Table 4 – Maturity Levels

The inconsistency between shifts and teams indicates a lack of standardized procedures, which is a hallmark of Level 1.

A control system, particularly in the context of IACS, is defined as a collection of hardware and software components used to monitor and control industrial processes. This includes PLCs, RTUs, SCADA software, HMIs, and communication networks.

“Control system: A set of hardware and software components that work together to monitor and control industrial or process operations.”

— ISA/IEC 62443-1-1:2007, Clause 3.3.5 – Terminology

While the other options describe security functions or consequences, only Option C accurately describes what a control system is.

The ISA/IEC 62443 series is structured into logical groups to address different aspects of industrial cybersecurity. Historically, the series was organized into Parts 1 through 4, covering general concepts, management system requirements, system requirements, and component requirements. As the standard evolved, the need arose to address sector-specific and application-specific cybersecurity needs without modifying the core requirements.

To address this, ISA introduced the concept of cybersecurity profiles. These profiles allow industries (such as oil and gas, power, water, or manufacturing) to select and tailor existing ISA/IEC 62443 requirements for their specific operational context while preserving consistency with the base standard.

The Profiles Group is formally designated as ISA/IEC 62443-5-x. This numbering clearly distinguishes profiles from foundational requirements and ensures that:

No new security requirements are created

Existing requirements are selected, scoped, and referenced appropriately

Alignment with Parts 2, 3, and 4 is preserved

By allocating profiles to the 5-x series, ISA ensures modularity and prevents fragmentation of the standard. Profiles serve as an application layer over existing requirements, enabling consistent adoption across sectors without redefining core security controls.

Parts 3-x and 4-x remain dedicated to system and component requirements, while 6-x does not exist in the published structure for profiles. Therefore, 5-x is the correct and formally defined answer.

ISA/IEC 62443 frequently references common industrial protocols when discussing network security, segmentation, and secure communications. MODBUS TCP/IP is one of the most widely deployed industrial protocols and is explicitly recognized as operating over TCP port 502.

Step 1: Protocol context

MODBUS TCP/IP is the Ethernet-based adaptation of the MODBUS protocol, enabling communication between PLCs, HMIs, and SCADA systems over IP networks. Unlike HTTP or HTTPS, MODBUS does not include native authentication or encryption.

Step 2: Port assignment

The standard TCP port assigned to MODBUS TCP/IP is 502, which is well known and commonly targeted by attackers. ISA/IEC 62443 highlights that well-known ports increase exposure and therefore require compensating controls such as firewalls, segmentation, and deep packet inspection.

Step 3: Security implications

Because port 502 traffic can carry control commands directly affecting physical processes, the standard emphasizes controlling and monitoring communications using this port within defined zones and conduits.

Step 4: Why other options are incorrect

Port 21 is used for FTP

Port 80 for HTTP

Port 443 for HTTPS

Thus, the correct and standards-aligned answer is 502.

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.