ISA-IEC-62443 ISA Exam Lab Questions

 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.

The reference model provides the overall conceptual basis in the design of an appropriate security program. It defines the common terminology, concepts, and models that can be used by all stakeholders responsible for IACS security. The reference model describes the general characteristics of IACS, the typical threats and vulnerabilities, the security lifecycle phases, and the security levels. The reference model also introduces the concepts of zones and conduits, which are used to group and isolate assets with similar security requirements and to control the communication between them. References

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

The Open Systems Interconnection (OSI) model is a framework that describes the functions of a networking system. The OSI model categorizes the computing functions of the different network components, outlining the rules and requirement needed to support the interoperability of the software and hardware that make up the network1.

The OSI model consists of seven abstraction layers arranged in a top-down order: Physical, Data Link, Network, Transport, Session, Presentation, and Application. The Transport layer is the fourth layer in the OSI model, and it is responsible for ensuring reliable and efficient data transfer between the Network layer and the Session layer2. The Transport layer uses protocols such as Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) to provide end-to-end communication services, such as error detection and correction, flow control, congestion control, and segmentation2.

The image that you sent shows a 3D representation of the OSI model, with the layers stacked on top of each other. The missing layer is the Transport layer, which isrepresented by a pink box with a white arrow pointing to it. The arrow is labeled “TCP, UDP”.

1: What is the OSI Model? 7 Network Layers Explained | Fortinet 2: What is OSI Model | 7 Layers Explained - GeeksforGeeks