Free Practice Questions for ISA ISA-IEC-62443 Exam

In the ISA/IEC 62443 framework, Security Levels (SLs) are categorized into three distinct types:

Target SL (SL-T) – The security level required based on risk assessment

Capability SL (SL-C) – The level a component or system can support

Achieved SL (SL-A) – The level actually implemented in the system

“Three types of security levels are defined:

Target (SL-T): derived from risk analysis

Capability (SL-C): supported by the product or system

Achieved (SL-A): implemented and operational in the environment”

— ISA/IEC 62443-1-1:2007, Clause 3.2.4 and Table 3

This classification supports gap analysis and helps asset owners ensure their system meets both required and feasible security levels.

ISA/IEC 62443 recognizes that organizations may align their IACS cybersecurity programs with other authoritative guidance. Within the NIST Special Publications, SP 800-82 is the document specifically dedicated to Industrial Control Systems security.

Step 1: Scope of SP 800-82

SP 800-82 provides guidance tailored to ICS environments, including SCADA, DCS, and PLC-based systems. It addresses availability, safety, and real-time constraints similar to ISA/IEC 62443.

Step 2: Complementary relationship

ISA/IEC 62443 and SP 800-82 are often used together: ISA/IEC 62443 provides auditable requirements, while SP 800-82 provides practical implementation guidance.

Step 3: Why other options are incorrect

SP 800-30 focuses on risk assessment

SP 800-53 defines general security controls

SP 800-171 focuses on protecting CUI in non-federal systems

Therefore, the correct answer is SP 800-82.

For industrial networks, the most effective approach is to use IACS-specific firewalls that perform deep packet inspection (DPI) of industrial protocols (e.g., Modbus, DNP3, OPC UA).

“Industrial-specific firewalls with DPI capabilities can inspect control system protocols and enforce granular access control without disrupting time-sensitive operations.”

— ISA/IEC 62443-3-3:2013, SR 5.1 – Zone Boundary Protection

Unlike generic IT firewalls, IACS-specific firewalls:

Understand OT protocols

Enforce real-time constraints

Support deterministic traffic flows

IACS stands for “Industrial Automation and Control Systems.” The ISA/IEC 62443 series defines IACS as systems used for industrial automation, process control, and related functions. These include systems such as Distributed Control Systems (DCS), SCADA systems, and PLCs. The term encompasses all electronic systems, networks, and equipment used to automate industrial processes.

ISA/IEC 62443-3-2 specifically describes the methodology for conducting risk assessments within industrial automation and control systems (IACS). This part of the standard provides guidance on identifying risks, assigning Security Levels, and making design decisions during the Assess phase of the IACS Cybersecurity Lifecycle.

According to the ISA/IEC 62443 Cybersecurity Fundamentals, the risk matrix is a tool used to assess the risk of a particular event. The risk matrix is divided into three categories: likelihood, consequence, and risk. The likelihood is the probability that an event will occur, the consequence is the impact that the event will have, and the risk is the combination of the two. In this case, the risk of a medium likelihood event with high consequence is a high risk, as shown by the red cell in the matrix. References:

ISA/IEC 62443 Cybersecurity Fundamentals

[ISA/IEC 62443 Cybersecurity Certificate Program]

[Cybersecurity Library]

[Using the ISA/IEC 62443 Standard to Secure Your Control Systems]

ISA/IEC 62443-3-3 provides the list of Foundational Requirements (FRs) for IACS cybersecurity, mapping security controls to each FR to address risks identified during the risk assessment process. The seven FRs include: Identification & Authentication Control (IAC), Use Control (UC), System Integrity (SI), Data Confidentiality (DC), Restricted Data Flow (RDF), Timely Response to Events (TRE), and Resource Availability (RA).

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.

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.

Asymmetric (public) key algorithms are a type of cryptographic algorithms that require more than one key. Asymmetric key algorithms use a pair of keys, one for encryption and one for decryption, that are mathematically related but not identical1. The encryption key is usually made public, while the decryption key is kept private. This allows anyone to encrypt a message using the public key, but only the intended recipient can decrypt it using the private key1. Asymmetric key algorithms are also known as public key algorithms or public key cryptography1. Asymmetric key algorithms are used for various purposes, such as digital signatures, key exchange, and encryption2. Some examples of asymmetric key algorithms are RSA, Diffie-Hellman, ElGamal, and Elliptic Curve Cryptography2.