blockchain security: a comparative analysis of threats and countermeasures

Blockchain technology, as one of the transformative innovations of the last decade, has garnered significant attention across diverse domains such as financial services, healthcare, supply chain management, energy, the internet of things (iot), and smart contracts. characterized by key features such as transparency, immutability, decentralization, distributed and advanced traceability, blockchain serves as a powerful tool for transforming informational infrastructures and fostering trust among stakeholders. however, alongside these advantages, blockchain faces critical security challenges that threaten its widespread adoption, including data breaches and risks to data integrity. this study examines the structure and architecture of blockchain, identifying major security threats such as ddos attacks, phishing, majority attacks, sybil attacks, and other critical vulnerabilities. additionally, it analyzes existing countermeasures to address these threats, evaluating their strengths, limitations, and areas for improvement. furthermore, through comparative analysis, this research provides a comprehensive and practical perspective for researchers, developers, and decision-makers to enhance blockchain resilience and applicability.