# Dynamic Risk Assessment in Cybersecurity: A Systematic Literature Review
###### Abstract  
Traditional information security risk assessment (RA) methodologies and standards, adopted by information security management systems and frameworks as a foundation stone towards robust environments, face many difficulties in modern environments where the threat landscape changes rapidly and new vulnerabilities are being discovered. In order to overcome this problem, dynamic risk assessment (DRA) models have been proposed to continuously and dynamically assess risks to organisational operations in (near) real time. The aim of this work is to analyse the current state of DRA models that have been proposed for cybersecurity, through a systematic literature review. The screening process led us to study 50 DRA models, categorised based on the respective primary analysis methods they used. The study provides insights into the key characteristics of these models, including the maturity level of the examined models, the domain or application area in which these models flourish, and the information they utilise in order to produce results. The aim of this work is to answer critical research questions regarding the development of dynamic risk assessment methodologies and provide insights on the already developed methods as well as future research directions.  
cybersecurity; dynamic risk assessment; machine-learning; quantitative risk assessment +
Footnote †: journal: _Future Internet_  
spot and to make quick decisions on how to best mitigate this risk. For the purpose of our research, we characterised as dynamic, any system, model, or framework that used as input any kind of real-time data coming from its environment and, based on them, calculated the risk.  
DRA constitutes a very useful tool that could help to evaluate and counter cyber threats in current environments, which are complex and evolve rigorously, as well as to maintain the organisation's security posture or improve it to the most appropriate level. Thus, our motivation to write this article stemmed from the need to analyse the current status around the area of DRA in cybersecurity. Our work focused on the DRA models proposed in the literature in the area of cybersecurity, regardless of the domain in which these models have been applied or the analysis method they have used. We tried to examine this topic holistically, having no prior limitation.  
The main contribution of this paper was an analysis of the existing literature regarding DRA schemes in the field of cybersecurity to identify methods and techniques that were being applied in the respective models. We further classified these schemes, based on the primary analysis method they utilised for the risk assessment process, and we identified the domain(s) that each of them was being applied. Moreover, we examined both the output (quantitative or qualitative risk analysis) that these models utilised, as well as the input data they used. Finally, we examined the proposed models with respect to their maturity status. To the best of the authors' knowledge, this is the first literature review focused on DRA in the field of cybersecurity, regardless of the proposed approach and the domain in which these models are being applied.  
The rest of this paper is structured as follows: Section 2 presents related work and Section 3 presents the research methodology used for this work. Section 4 provides the detailed results of the DRA models found in the literature, categorised under the primary analysis method they apply. Meanwhile, Section 5 undertakes a thorough discourse on these results. Section 6 concludes the study.