Blockchain security threats: A comprehensive classification and impact assessment

Blockchain technology has become a key force driving social, economic, and technological progress. Its features, such as decentralization, transparency, and immutability, have demonstrated enormous application potential across various fields, including finance, healthcare, government, and the Internet of Things. However, as the application of blockchain continues to expand, associated security issues have become increasingly prominent. The unique characteristics of blockchain systems present a series of complex challenges in terms of security. To clarify the security challenges and risks of blockchain technology, this paper provides a detailed and comprehensive literature review. This paper classifies the main security threats faced by blockchain technology systematically, according to its different layers. Based on this classification, we further refine the types of attacks and summarize them. In addition, we compile and organize the impact of each attack on blockchain systems and participants, making it easier to understand the damages caused by different attacks in a more intuitive and effective way. Finally, the paper identifies future research directions in blockchain security, offering guidance for researchers interested in further exploring this field.