Edinburgh Napier University

  This study provides a comprehensive overview of blockchain technology, discusses its characteristics, and explains the hierarchical structure of the blockchain. Additionally, the study provides an in-depth analysis of various security threats and vulnerabilities in blockchain systems. It categorises the threats into different classes, including service-based, identity-based, network-based, manipulation-based, and those associated with smart contracts. The study delves into specific attacks such as double spending, collusion, and quantum attacks, and discusses countermeasures to enhance the security of blockchain transactions. It also highlights the challenges posed by network threats like DOS/DDoS and MITM attacks, and the implications of bugs and malware on the integrity of blockchain systems. The research highlights the importance of robust security protocols and the need for ongoing vigilance against evolving threats in the blockchain ecosystem.