Companies face increasing pressure to protect themselves and their customers from security threats. Security by design is a proactive approach that builds security into all aspects of a system from the ground up, rather than adding it on as an afterthought. By taking security into account at every stage of development, organizations can create systems that are more resistant to attacks and better able to recover from them if they do occur. One of the most relevant practices is threat modelling, i.e. the process of identifying and analysing the security threat to an information system, application, or network. These processes require security experts with high skills to anticipate possible issues: therefore, it is a costly task and requires a lot of time. To face these problems, many different automated threat modelling methodologies are emerging. This paper first carries out a systematic literature review (SLR) aimed at both having an overview of the automated threat modelling techniques used in literature and enumerating all the tools that implement these techniques. Then, an analysis was carried out considering four open-source tools and a comparison with our threat modelling approach using a simple, but significant case study: an e-commerce site developed on top of WordPress.

Fifth-generation technology standard for broadband cellular networks, 5G, delivers a significant increase in data speeds and capacity, as well as new capabilities such as higher energy efficiency, lower latency, and the ability to connect a large number of devices. These advances come with a new set of security challenges, as 5G networks will be more complex and integrated with critical infrastructure than previous generations. In order to correctly address such challenges there is the need for fine-grained threat models, that collect a set of well-detailed threats, each of them clearly addressing a system component, taking into account how components are connected and interact with each other, the specific technology and/or the protocols are involved. A fine-grained threat model can be used to support the definition of a penetration testing plan or to identify and verify the effectiveness of technical countermeasures. This paper extends an existing automated threat modelling methodology focusing on 5G architecture and defines a process to build in a systematic way the catalogue of threats on which the technique relies. In order to obtain such results, we extended our modelling technique, in order to model 5G architectures, defined a process to extend our methodology to address additional domains and applied the approach to a concrete case study, applying our technique to a common 5G open-source architecture proposed by our industrial partner. The main contribution of this paper can be summarized as follows(I) A technique to systematically produce an extension of our modelling technique and a threat catalogue for a specific Domain, (ii) A 5G systems threat catalogue, (iii) A 5G systems graph-based modelling technique. As an additional result, we validated our approach, applying our technique in a real context and involving industrial experts for the evaluation of the generated fine-grained threat model.