# A Resilience Engineering Approach for the Risk Assessment of IT Services
## 1 Introduction
Accordingly, most studies on resilience engineering focused on the risk of safety accidents involving modern industrial-technological systems, whose complexity makes reactive risk assessment approaches unsuitable for comprehending how and why accidents occur [21; 22]. This is in line with the findings by [PERSON] et al. [23], who observed that the majority of FRAM applications concern safety problems in manufacturing, transportation, or power plant contexts, while the use of such an approach in business and operational research domains is still limited. In particular, there is a need to analyze and manage the so-called \"black swans\", i.e., unpredictable risks that differ from what is usually expected and are very difficult to envisage. For example, due to their unpredictability, human factors are considered a potential source of errors and malfunctions, requiring a proactive approach to ensure effective safety management [13]. To deal with them, as stressed by [PERSON] [24], further research is needed to develop risk assessment procedures tailored for the management of \"critical infrastructures\", whose vulnerability is related to threats due to human actions that cannot be properly managed using traditional risk assessment approaches, as in the case of security infrastructures and the reliability of IT services [25; 26]. It must be noted that also in the latter context, recent cases of failures and malfunctioning have caused significant problems: for example, the fire that seriously damaged Europe's largest cloud services firm, OVHcloud, in 2021 [27], or the outage that occurred in 2021, which involved one of the major Content Delivery Network (CDN) providers [28]. Similarly, several authors pointed out the need to use a resilience engineering approach to augment risk analysis of IT services in the healthcare domain, where system failure must be rigorously avoided [29; 30]. Moreover, it must be noted that IoT technologies attract great interest from cybercriminals; consequently, as observed by [PERSON] et al. [31], the potential for significant damage to an enterprise network can be substantial. All these occurrences also show the unpredictable nature of risks that might affect IT services and cloud computing. The need for a proper risk assessment approach in this sector was pointed out by several studies [32; 33], which mainly outlined the provision of risk assessment frame works capable of dealing with the variability, unpredictability, and vulnerability of these complex systems. In the IT context, on the one hand, in recent years numerous efforts have been carried out to augment risk assessment approaches that can guarantee cloud security, as reported, for example, by the MEDINA project financed by the European Union [34]. On the other hand, most risk assessment tools in this domain rely on a reactive approach, while only a few of them take into account supply chain risks [35] and the elicitation of software requirements for complex systems [36]. Hence, a \"Safety II\" approach is needed to explain performance variability in such a context, and FRAM appears to be the proper tool for systemic safety assessment in this complex and dynamic domain [37]. Based on the above considerations, the current study aims to reduce this research gap by augmenting knowledge of the risk management of IT services by means of a resilience engineering approach through the application of FRAM to the case of cloud migration. In particular, a risk assessment framework was developed to provide a structured approach based on FRAM that can be used at an operational level, which we think can contribute to the lack of practical tools to apply functional resonance [38] and a multidisciplinary approach for the requirements elicitation of IT services [30]. In more detail, the remainder of the paper is as follows: The next section concerns the study's materials and methods and is divided into two parts.