# Security Assessment of Agriculture IoT (AIoT) Applications
## 2 Materials and Methods
### The Cybersecurity Assessment Process  
The standardization of a cybersecurity assessment process was mainly driven by the initiative of the International Society for Automation (ISA) and the American National Standards Institute (ANSI) started in 2002. Originally named ANSI/ISO-99, it was later renamed as the ANSI/ISA-62443 standard series. In 2009, the European standardization committees utilized a fundamental concept from the original ANSI/ISA-62443 standard to introduce the IEC 62443 cybersecurity standard series [1; 2; 3; 4; 5; 6; 7; 8].  
The industrial security standard IEC 62443 specifies a security assessment process for the overall system domain, both from the system and component view. Different security aspects are relevant for the security assessment, and these aspects must be analyzed. The appropriated analysis results are documented in a security documentation and define the security determinations in a security plan.  
The security assessment process flow defines five dedicated steps, as shown in Figure 2. Each step must be performed to carry out a standard cybersecurity assessment.  
An assessment process should always follow the same procedures. This is important because a cybersecurity assessment must be repeated periodically to identify new types of vulnerabilities and improve the system against new attack vectors. This enables ongoing and comparable evaluations.  
The process defines five main activity steps and one decision and assessment step.  
The following overview of the process steps gives a short introduction. In the following chapter, the steps and the necessary activities are explained in detail.  
* SuC Identification:  
Activity: accurately describe the SuC for which the security assessment shall take place. It is important to define the borders of the system to define what is and is not part of the SuC.  
* High-level cybersecurity risk analysis  
Perform a high-level security risk analysis of the system defined by the SuC description. Determine the Target Security Level (SL-T). This is the minimum cybersecurity level the system must have.  
* Split into zones and conduits  
Split the SuC into zones (system areas with similar criticality) and define the communication paths (conduits) which connect the zones. This activity prepares the system for the detail cybersecurity assessment.  
* Detail cybersecurity risk analysis  
Perform for each zone and conduit a detailed risk analysis. The analysis determines existing threats and vulnerabilities. The standard IEC 62443 provides seven Foundational Requirement (FR) groups to support the analysis. By the definition of a suitable SL the standard provides a set of requirements that must be fulfilled and well-ordered in the seven FR groups. Each group specifies a set of sub-requirements, depending on the selected SL.  
* Tolerable risk assessment  
Figure 2: IEC 62443 cybersecurity process steps.  
Repeat the detailed risk analysis in a loop manner until the SL-T matches the Capability SL (SL-C). The system or component capability level describes the maximal realizable SL by implementation. When no match can be targeted, the system does not provide the necessary SL. In this case, a possible solution may be to embed the entire system in a safe, enveloping operating environment.
* Document requirements and countermeasures  
Document all the security implementations, security requirements and any security artefacts to create a final cybersecurity report. The actual security implementation documents the Archived SL (SL-A).