In order to realise the true potential of blockchain-based applications, the first step is to understand the associated risks and vulnerabilities. Blockchain-based applications are considered to be less vulnerable but there are certain security risks (eg, Sybil and Doublespending, etc) within the blockchain-based applications that are debatable. There exists no comprehensive blockchain-based security reference model to systematically evaluate the security of blockchain-based applications. In this study, we illustrate the PhD thesis research work to build an ontology-based reference model for security risk management of blockchain-based applications. A reference model would establish a common ground and systematic understanding for professionals and researchers regarding the security of the blockchain-based application.