An evaluation of potential attack surfaces based on attack tree modelling and risk matrix applied to self-sovereign identity

Self-Sovereign Identity (SSI) empowers users to govern their digital identity and personal data. This approach has changed the identity paradigm where users become the central governor of their identity; hence the rapid growth of the SSI model. Utilizing the security and privacy properties of blockchain, together with other security technologies, SSI purports to provide a robust security and privacy service. However, this governing power for users comes with a greater accountability and security risk, as not all users are capable or trained in its use and therefore in its efficient application. This trade-off requires a systematic evaluation of potential attacks on the SSI system and their security risks. Hitherto, there have been no noteworthy research studies performed to evaluate potential attacks on the SSI system and their security risks. This paper proposes an easy, efficient and economical approach to perform an evaluation of potential attacks on the SSI system and their security risks. This approach utilises a combination of an attack tree model and risk matrix model to perform this evaluation of potential attacks and their security risks, in addition to outlining a systematic approach including describing the system architecture and determining its assets in order to perform this evaluation of potential attacks and their security risks. This evaluation work has identified three potential attacks on the SSI system: faking identity, identity theft and distributed denial of service attacks, and performed their security risk evaluation utilising the proposed approach. Finally, this paper has proposed several mitigation strategies for the three evaluated attacks on the SSI system. This proposed evaluation approach is a systematic and generalised approach for evaluating attacks and their security risks, and can be applied to any other IT system.