# A Configurable Dependency Model of a SCADA System for Goal-Oriented Risk Assessment
## 5 The SCADA Dependency Model
### Key Areas Overview
The important role of human factors in SCADA systems is extensively discussed in the literature [19]. Errors made by human operators, who remotely control and monitor SCADA systems, or engineers, who design and configure SCADA systems, may and in many cases have led to undesirable or even disastrous consequences [4]. A significant number of paragons in the generic dependency model are dependencies of the key area that we named **Employees**. The model indicates a need for ensuring that all roles and experts, who are involved in the design, development, operation and monitoring of a SCADA system (including but not limited to software and system engineers, information security engineers, managers, physical security personnel and operators), should receive the required training and satisfy a number of requirements discussed below. Operators must be competent and diligent, and they should be able to undertake manual supervision of a system when required. All intentions shall be monitored and observed, which shall help to identify malicious operators. The SCADA operators, who are located remotely and do not have an opportunity to observe the processes in real time, judge the state of physical processes only based on the reports from the SCADA system via HMI. Hence, not only the correctness and precision of the information is important but also the effectiveness of the information representation. The importance of the interactions between human operators and machines should be recognised in every SCADA system, and adverse effects of poor interactions should be minimised. Training provided to the operators shall start with the analysis of training needs; both individual and team training sessions are required. Use case scenarios shall be examined during training sessions. Given the level of responsibility of the operators of the SCADA system, a background check shall take place as a part of the procedures for new personnel. Procedures for leaving personnel shall also be in place. Staff retention programs shall be in place. The model also includes such elements as health and safety, required knowledge and expertise, appropriate level of awareness, and effective administration of human resources. Human resources management is also accounted for in the generic dependency model. SCADA systems that use advanced technology require highly-skilled personnel, who will keep their knowledge up-to-date through continuous training. External dependencies also play an important role for the success of safe and secure operations within a SCADA system. All external factors outlined by the participants are captured under the key area **External Dependencies (Environment)**. As one of the external dependencies, third parties upon which SCADA processes rely were identified. The third party list includes vendors, service providers, equipment and system designers, equipment and system integrators (when these activities are outsourced), customers, manufacturers and all stakeholders of a supply chain. Other dependencies of this paragon include threat agents, industry working groups, press and media, and government and standardisation bodies.