Threat modelling on data sharing

In recent years, the proliferation of Internet access has ushered in a new era of unprecedented human interaction and connectivity. This digital expansion offers tremendous benefits, enabling rapid and borderless sharing of experiences. However, this surge in Internet use also exposes individuals to greater privacy risks as the abundance of personal data becomes easily accessible to a wide audience. Even when a service's security systems are of high quality, people are never completely safe from cyber-attacks. Personal Information, even that which users might consider less important, could be exploited for malicious purposes. It is for these reasons that the urgency of identifying potential threats and privacy issues emerges, a task that is anything but simple. The methodology examined in this thesis is the threat model, a concept that is already well established in several areas, including software development and complex systems design. Specifically, this thesis focuses on the development of a threat model adapted to data sharing systems. The model is designed to analyse the intricate relationships, properties, and potential threats within such systems, with the goal of identifying mitigation strategies to improve user security. Once the development of the model was completed, it underwent validation to ensure its correctness and effectiveness. The validation process included testing the model with two real-world use cases, affirming its ability to accurately detect vulnerabilities and threats.