ISA-IEC-62443 ISA/IEC 62443 Cybersecurity Fundamentals Specialist Questions and Answers

The primary responsibility of the network layer of the Open Systems Interconnection (OSI) model is to forward packets, including routing through intermediate routers. The network layer is the third layer from the bottom of the OSI model, and it is responsible for maintaining the quality of the data and passing and transmitting it from its source to its destination. The network layer also assigns logical addresses to devices, such as IP addresses, and uses various routing algorithms to determine the best path for the packets to travel. The network layer operates on packets, which are units of data that contain the source and destination addresses, as well as the payload. The network layer forwards packets from one node to another, using routers to switch packets between different networks. The network layer also handles host-to-host delivery, which means that it ensures that the packets reach the correct destination host.

The other choices are not correct because:

• B. Gives transparent transfer of data between end users. This is the responsibility of the transport layer, which is the fourth layer from the bottom of the OSI model. The transport layer provides reliable and error-free data transfer between end users, using protocols such as TCP and UDP. The transport layer operates on segments, which are units of data that contain the source and destination port numbers, as well as the payload. The transport layer also handles flow control, congestion control, and multiplexing.
• C. Provides the rules for framing, converting electrical signals to data. This is the responsibility of the data link layer, which is the second layer from the bottom of the OSI model. The data link layer provides the means for transferring data between adjacent nodes on a network, using protocols such as Ethernet and WiFi. The data link layer operates on frames, which are units of data that contain the source and destination MAC addresses, as well as the payload. The data link layer also handles error detection, error correction, and media access control.
• D. Handles the physics of getting a message from one device to another. This is the responsibility of the physical layer, which is the lowest layer of the OSI model. The physical layer provides the means for transmitting bits over a physical medium, such as copper wire, fiber optic cable, or radio waves. The physical layer operates on bits, which are the smallest units of data that can be either 0 or 1. The physical layer also handles modulation, demodulation, encoding, decoding, and synchronization.

References:

• The OSI Model – The 7 Layers of Networking Explained in Plain English1
• Network Layer in OSI Model2
• OSI model3

In cybersecurity, a demilitarized zone (DMZ) refers to a physical or logical subnetwork that contains and exposes an organization's external-facing services to an untrusted network, typically the internet. The main characteristic of a DMZ is that it acts as a buffer zone between the public internet and the private network. This allows for internet access through the firewall while keeping the internal network secure. Internet-facing servers are placed in the DMZ so that they are separated from the rest of the internal network. By doing so, if a server in the DMZ is compromised, the attacker would not have direct access to the internal network. This architecture is commonly used to host services such as web servers, mail servers, and FTP servers. Choice C is the most closely associated with the deployment of a DMZ as it allows for regulated and monitored internet access through a firewall.

Defense in depth is a concept of cybersecurity that involves applying multiple layers of protection to a system or network, so that if one layer fails, another layer can prevent or mitigate an attack. Defense in depth is based on the principle that no single security measure is perfect or sufficient, and that multiple countermeasures can provide redundancy and diversity of defense. Defense in depth can also increase the cost and complexity for an attacker, as they have to overcome more obstacles and exploit more vulnerabilities to achieve their goals. Defense in depth is one of the key concepts of the ISA/IEC 62443 series of standards, which provide guidance and best practices for securing industrial automation and control systems (IACS). The standards recommend applying defense in depth strategies at different levels of an IACS, such as the network, the system, the component, and the policy and procedure level. The standards also define different zones and conduits within an IACS, which are logical or physical groupings of assets that share common security requirements and risk levels. By applying defense in depth strategies to each zone and conduit, the security of the entire IACS can be improved. References:

• ISA/IEC 62443-1-1:2009, Security for industrial automation and control systems - Part 1-1: Terminology, concepts and models1
• ISA/IEC 62443-3-3:2013, Security for industrial automation and control systems - Part 3-3: System security requirements and security levels2
• ISA/IEC 62443-4-1:2018, Security for industrial automation and control systems - Part 4-1: Product security development life-cycle requirements3
• ISA/IEC 62443-4-2:2019, Security for industrial automation and control systems - Part 4-2: Technical security requirements for IACS components4

According to the ISA/IEC 62443-3-2 standard, a security zone is a grouping of systems and components based on their functional, logical, and physical relationship that share common security requirements. The primary objective of defining a security zone is to apply a consistent level of protection to the assets within the zone, based on their criticality and risk assessment. A security zone may contain assets from different vendors, different levels in the Purdue model, or different physical locations, as long as they have the same security requirements. A security zone may also be subdivided into subzones, if there are different security requirements within the zone. A conduit is a logical or physical grouping of communication channels connecting two or more zones that share common security requirements.

References:

• ISA/IEC 62443-3-2:2020, Security for industrial automation and control systems - Part 3-2: Security risk assessment for system design, Clause 4.3.21
• ISA/IEC 62443-1-1:2009, Security for industrial automation and control systems - Part 1-1: Terminology, concepts and models, Clause 3.2.42

One of the primary goals of providing a framework that addresses secure product development lifecycle requirements is to ensure that security policies and procedures are well-documented. This objective is crucial because it establishes a structured and standardized approach to security that is integrated throughout the development process of software or systems. This framework helps in aligning the development process with security best practices, thereby mitigating risks associated with security vulnerabilities. Documentation of security policies and procedures ensures that security considerations are consistently applied and that compliance with relevant standards, such as ISA/IEC 62443, is maintained. This foundational approach supports the overall security posture by embedding security considerations directly into the lifecycle of product development, rather than addressing security as an afterthought.

One of the trends that has increased the security risks for industrial automation and control systems (IACS) is the integration of these systems with business and enterprise systems, such asenterprise resource planning (ERP), manufacturing execution systems (MES), and supervisory control and data acquisition (SCADA). This integration exposes the IACS to the same threats and vulnerabilities that affect the business and enterprise systems, such as malware, denial-of-service attacks, unauthorized access, and data theft. Moreover, the integration also creates new attack vectors and pathways for adversaries to compromise the IACS, such as through remote access, wireless networks, or third-party devices. Therefore, the integration of IACS with business and enterprise systems is a trend that has caused a significant percentage of security vulnerabilities. References: ISA/IEC 62443 Standards to Secure Your Industrial Control System, page 1-2.

A Process Hazard Analysis (PHA) is a systematic and structured method of identifying and evaluating the potential hazards and risks associated with an industrial process. A PHA can help to identify the possible causes and consequences of undesired events, such as equipment failures, human errors, cyberattacks, natural disasters, etc. A PHA can also provide recommendations for reducing the likelihood and severity of such events, as well as improving the safety and security of the process. A PHA is one of the most frequently used analysis methods as an input to a security risk assessment, as it can help to identify the assets, threats, vulnerabilities, and impacts related to the process, and provide a basis for determining the security risk level and the appropriate security countermeasures. A PHA is also a requirement of the ISA/IEC 62443 standard, as part of the security program development and implementation phase12. References: 1: ISA/IEC 62443-2-1: Security for industrial automation and control systems: Establishing an industrial automation and control systems security program 2: ISA/IEC 62443-3-2: Security for industrial automation and control systems: Security risk assessment for system design

The selection of countermeasures is driven by the output from a risk assessment, which identifies the risks and their associated likelihood and consequences for each zone and conduit in the industrial automation and control system (IACS). The risk assessment also determines the target security level (SL-T) for each zone and conduit, which represents the desired level of protection against the identified threats. The countermeasures are then selected based on the SL-T and the existing security level (SL-A) of the zone and conduit, as well as the cost and feasibility of implementation. The countermeasures should aim to reduce the risk to an acceptable level by increasing the SL-A to meet or exceed the SL-T. References: ISA/IEC 62443-3-2:2018 - Security risk assessment for system design, ISA/IEC 62443-3-3:2013 - System security requirements and security levels, ISA/IEC 62443 Cybersecurity Fundamentals Specialist Training Course

Authorization security policy is the primary factor that determines access privileges for user accounts. Authorization security policy is the function of specifying access rights or privileges to resources, which is related to general information security and computer security, and to accesscontrol in particular1. Authorization security policy defines who can access what resources, under what conditions, and for what purposes. Authorization security policy should be aligned with the business objectives and security requirements of the organization, and should be enforced by appropriate mechanisms and controls. Authorization security policy should also be reviewed and updated regularly to reflect changes in the environment, threats, and risks2. Authorization security policy is an essential part of the ISA/IEC 62443 standard, which provides a framework for securing industrial automation and control systems (IACS). The standard defines four security levels (SL) that represent the degree of protection against threats, and specifies the security capabilities that should be implemented for each SL. The standard also provides guidance on how to conduct a security risk assessment, how to define security zones and conduits, and how to apply security policies and procedures to the IACS environment34 . References:https://bing.com/search?q=authorization+security+policy

https://learn.microsoft.com/en-us/aspnet/core/security/authorization/policies?view=aspnetcore-7.0

The File Transfer Protocol (FTP) is an application layer protocol that moves files between local and remote file systems. It runs on top of TCP, like HTTP. To transfer a file, 2 TCP connections are used by FTP in parallel: control connection and data connection. The control connection is used to send commands and responses between the client and the server, while the data connection is used to transfer the actual file. FTP is one of the standard communication protocols defined by the TCP/IP model and it does not fit neatly into the OSI model. However, since the OSI model is a reference model that describes the general functions of each layer, FTP can be considered as an application layer protocol in the OSI model, as it provides user services and interfaces to the network. The application layer is the highest layer in the OSI model and it is responsible for providing various network services to the users, such as email, web browsing, file transfer, remote login, etc. The application layer interacts with the presentation layer, which is responsible for data formatting, encryption, compression, etc. The presentation layer interacts with the session layer, which is responsible for establishing, maintaining, and terminating sessions between applications. The session layer interacts with the transport layer, which is responsible for reliable end-to-end data transfer and flow control. The transport layer interacts with the network layer, which is responsible for routing and addressing packets across different networks. The network layer interacts with the data link layer, which is responsible for framing, error detection, and medium access control. The data link layer interacts with the physical layer, which is responsible for transmitting and receiving bits over the physical medium. References:

• File Transfer Protocol (FTP) in Application Layer1
• FTP Protocol2
• What OSI layer is FTP?3

According to the ISA/IEC 62443-1-1 standard, an industrial automation and control system (IACS) is defined as a collection of personnel, hardware, and software that can affect or influence the safe, secure, and reliable operation of an industrial process. The hardware and software components of an IACS include the control system, which is the combination of control devices, networks, and applications that perform the control functions for the industrial process. The control system may consist of various types of devices, such as distributed control systems (DCS), programmable logic controllers (PLC), supervisory control and data acquisition (SCADA) systems, human-machine interfaces (HMI), remote terminal units (RTU), intelligent electronic devices (IED), sensors, actuators, and other field devices. The control system may also use commercial off-the-shelf (COTS) software and hardware, such as operating systems, databases, firewalls, routers, switches, and servers, to support the control functions and communication.

References:

• ISA/IEC 62443-1-1:2009, Security for industrial automation and control systems - Part 1-1: Terminology, concepts and models, Clause 3.2.11
• ISA/IEC 62443-2-1:2010, Security for industrial automation and control systems - Part 2-1: Establishing an industrial automation and control systems security program, Clause 3.2.12

Application whitelisting (AWL) is a technique that allows only authorized applications to run on a system, and blocks any unauthorized or malicious code from executing. AWL is one of the most effective methods for preventing malware infections and reducing the attack surface of a system. AWL can be implemented at different levels, such as the operating system, the network, or the application itself. AWL is especially useful forindustrial automation and control systems (IACS), which often run on legacy or proprietary platforms that are not compatible with traditional antivirus software or other security solutions. AWL can also help protect IACS from zero-day attacks, which exploit unknown vulnerabilities that have not been patched or detected by security vendors. AWL is recommended by the ISA/IEC 62443 standards as a key component of malicious code protection for IACS. According to the standards, AWL should be applied to all IACS components that support it, and should be configured and maintained according to the security policies and procedures of the organization. AWL should also be complemented by other security measures, such as network segmentation, zones and conduits, and patch management, to provide a defense-in-depth approach to IACS security. References:

• ISA/IEC 62443-3-3:2013, System security requirements and security levels, Section 5.2.3.41
• ISA/IEC 62443-2-1:2010, Establishing an industrial automation and control systems security program, Section 4.3.3.6.42
• ISA/IEC 62443-4-2:2019, Technical security requirements for IACS components, Section 4.2.3.43
• ISA/IEC 62443-3-2:2020, Security risk assessment for system design, Section 7.3.3.44
• ISA/IEC 62443-4-1:2018, Product development requirements, Section 5.2.3.45

ISO/IEC 15408, also known as the Common Criteria for Information Technology Security Evaluation, is an international standard that provides a framework for evaluating the security of IT products and systems. The purpose of the standard is to define a common set of requirements for the security functions and assurance measures of IT products and systems, and to establish a common methodology for conducting security evaluations. The standard allows users to specify their security needs and expectations in a Security Target (ST), which may be based on one or more Protection Profiles (PPs)that define security requirements for a class of products or systems. Vendors can then implement or claim compliance with the ST or PPs, and have their products or systems evaluated by independent testing laboratories against the security criteria defined in the standard. The standard also defines a scale of Evaluation Assurance Levels (EALs) that indicate the degree of confidence in the security of the evaluated product or system. The standard is intended to facilitate the development, procurement, and use of secure IT products and systems, and to promote the recognition and acceptance of evaluation results across different countries and regions. References:

• ISO/IEC 15408-1:2009 - Common Criteria Evaluation for IT Security - Nemko1
• Common Criteria - Wikipedia2
• ISO/IEC Standard 15408 — ENISA3

Phishing is a type of cyberattack that relies on a human weakness to succeed. Phishing is the practice of sending fraudulent emails or other messages that appear to come from a legitimate source, such as a bank, a government agency, or a trusted person, in order to trick the recipient into revealing sensitive information, such as passwords, credit card numbers, or personal details, or into clicking on malicious links or attachments that may install malware or ransomware on their devices. Phishing is a common and effective way of compromising the security of industrial automation and control systems (IACS), as it can bypass technical security measures by exploiting the human factor. Phishing can also be used to gain access to the IACS network, to conduct reconnaissance, to launch further attacks, or to cause damage or disruption to the IACS operations. The ISA/IEC 62443 series of standards recognize phishing as a potential threat vector for IACS and provide guidance and best practices on how to prevent, detect, and respond to phishing attacks. Some of the recommended countermeasures include:

• Educating and training the IACS staff on how to recognize and avoid phishing emails and messages, and how to report any suspicious or malicious activity.
• Implementing and enforcing policies and procedures for email and message security, such as using strong passwords, verifying the sender’s identity, and not opening or clicking on unknown or unsolicited links or attachments.
• Applying technical security controls, such as antivirus software, firewalls, spam filters, encryption, and authentication, to protect the IACS devices and network from phishing attacks.
• Monitoring and auditing the IACS network and devices for any signs of phishing attacks, such as anomalous or unauthorized traffic, connections, or activities, and taking appropriate actions to contain and mitigate the impact of any incidents. References:
• ISA/IEC 62443-1-1:2009, Security for industrial automation and control systems - Part 1-1: Terminology, concepts and models1
• ISA/IEC 62443-2-1:2009, Security for industrial automation and control systems - Part 2-1: Establishing an industrial automation and control systems security program2
• ISA/IEC 62443-2-4:2015, Security for industrial automation and control systems - Part 2-4: Security program requirements for IACS service providers3
• ISA/IEC 62443-3-3:2013, Security for industrial automation and control systems - Part 3-3: System security requirements and security levels4
• ISA/IEC 62443-4-2:2019, Security for industrial automation and control systems - Part 4-2: Technical security requirements for IACS components5

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.

 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.

 Modbus over Ethernet, also known as Modbus/TCP, is a protocol that encapsulates the Modbus/RTU data string inside the data section of the TCP frame. It then sets up a client/server exchange between nodes, using TCP/IP addressing to establish connections1. This makes it easy to manage in a firewall, because the firewall can filter the traffic based on the source and destination IP addresses and the TCP port number. The default TCP port for Modbus/TCP is 502, but it can be changed if needed. Modbus/TCP does not use any other ports or protocols, so the firewall rules can be simple and specific. References:

• 8: Open Modbus/TCP Specification, RTA Automation, 2010.
• [9]: Modbus Application Protocol Specification V1.1b3, Modbus Organization, 2012.

Datagram Transport Layer Security (DTLS) and Secure Sockets Layer (SSL) are both commonly used protocols for managing secure data transmission on the Internet. DTLS is a variant of SSL that is designed to work over datagram protocols such as UDP, which are used for real-time applications such as voice and video. SSL is a protocol that provides encryption, authentication, and integrity for data transmitted over TCP, which is used for reliable and ordered delivery of data. Both DTLS and SSL use certificates and asymmetric cryptography to establish a secure session between the communicating parties, and then use symmetric cryptography to encrypt the data exchanged. DTLS and SSL are widely used in web browsers, email clients, VPNs, and other applications that require secure communication over the Internet. References:

• ISA/IEC 62443 Standards to Secure Your Industrial Control System, Module 3: Introduction to Cryptography, pages 3-5 to 3-7
• Using the ISA/IEC 62443 Standards to Secure Your Control System, Chapter 6: Securing Communications, pages 125-126

Role-based access control (RBAC) is a method of restricting access to resources based on the roles of individual users within an organization. RBAC assigns permissions and responsibilities to roles, rather than to individual users, and then assigns users to those roles. This way, users can only perform the actions that are relevant and necessary for their role, and not access or modify any other resources that are beyond their scope of authority. RBAC is one of the security countermeasures that can be implemented in a defense-in-depth strategy, which is a layered approach to protect industrial automation and control systems (IACS) from cyber threats. RBAC can help prevent unauthorized access, misuse, or sabotage of IACS resources, as well as reduce the risk of human error or insider attacks.

References:

• ISA/IEC 62443-3-3:2013, Security for industrial automation and control systems - Part 3-3: System security requirements and security levels, Clause 5.3.2.11
• ISA/IEC 62443-2-1:2010, Security for industrial automation and control systems - Part 2-1: Establishing an industrial automation and control systems security program, Clause 6.2.2.32
• ISA/IEC 62443-4-1:2018, Security for industrial automation and control systems - Part 4-1: Product security development life-cycle requirements, Clause 5.2.3.23
• ISA/IEC 62443-4-2:2019, Security for industrial automation and control systems - Part 4-2: Technical security requirements for IACS components, Clause 4.2.3.24

 ISA-TR62443-2-3 is the technical report that describes the requirements for asset owners and industrial automation and control system (IACS) product suppliers that have established and are now maintaining an IACS patch management program. Patch management is the process of applying software updates to fix vulnerabilities, bugs, or performance issues in the IACS components. Patch management is an essential part of maintaining the security and reliability of the IACS environment. The technical report provides guidance on how to establish a patch management policy, how to assess the impact and risk of patches, how to test and deploy patches, and how to monitor and audit the patch management process. References: 1, 2, 3

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

A security conduit is a logical or physical grouping of communication channels connecting two or more zones that share common security requirements1. A zone is a grouping of systems and components based on their functional, logical, and physical relationship that share common security requirements1. Therefore, a security conduit consists of assets that enable or facilitatecommunication between zones, such as wiring, routers, switches, and network management devices. Controllers, sensors, transmitters, and final control elements are examples of assets that belong to a zone, not a conduit. Ferrous, thickwall, and threaded conduit including raceways are physical structures that may enclose or protect wiring, but they are not part of the communication channels themselves. Power lines, cabinet enclosures, and protective grounds are also not part of the communication channels, but rather provide power or protection to the assets in a zone or a conduit. References: 1: Key Concepts of ISA/IEC 62443: Zones & Security Levels | Dragos

At layer 4 of the OSI model, also known as the transport layer, the application that will handle a packet inside a host is identified by a TCP/UDP port number. A port number is a 16-bit integer that is assigned to a specific application or service that runs on a host. Port numbers are used to multiplex and demultiplex the data streams that are exchanged between hosts and end systems. Multiplexing is the process of combining multiple data streams into one, while demultiplexing is the process of separating one data stream into multiple ones. Port numbers are part of the header of the transport layer protocol data unit (PDU), which is called a segment for TCP and a datagram for UDP. The header contains the source port number and the destination port number, which indicate the applications that are involved in the communication. For example, if a host sends a packet to another host using the HTTP protocol, which runs on port 80 by default, the source port number would be a random number chosen by the sender, and the destination port number would be 80. The receiver would then use the destination port number to demultiplex the packet and deliver it to the HTTP application.

Port numbers are divided into three ranges: well-known ports (0-1023), registered ports (1024-49151), and dynamic or private ports (49152-65535). Well-known ports are reserved for common and standardized applications and services, such as HTTP (80), FTP (21), and SSH (22). Registered ports are assigned by the Internet Assigned Numbers Authority (IANA) to specific applications and services that request them, such as Skype (49175) and Minecraft (25565). Dynamic or private ports are not assigned by any authority and can be used by any application or service that needs them, such as ephemeral ports that are used for temporary connections.

The other options are not valid identifiers for the application that will handle a packet inside a host at layer 4 of the OSI model. A TCP/UDP application ID is not a term that is used in the OSI model or the TCP/IP model. A TCP/UDP host ID is not a term that is used in the OSI model or the TCP/IP model, and it would be more appropriate for layer 3, which is the network layer, where the host is identified by an IP address. A TCP/UDP registry number is not a term that is used in the OSI model or the TCP/IP model, and it would be more appropriate for layer 5, which is the session layer, where the registry number is used to identify a session between two hosts.

References:

• Transport Layer | Layer 4 | The OSI-Model1
• OSI model - Wikipedia2
• What is Layer 4 of the OSI Model? | Glossary | A10 Networks3
• What Are the 7 Layers of the OSI Model? | Webopedia4