With the increased access to the Internet of Things (IoT) technology and digital financial sectors, blockchain technology has received extensive attention in recent years. With the potential advantage of the immutable ledger in blockchain technology, it securely enables digital transactions in a decentralized manner. It has been widely applied in numerous applications such as the IoT, financial services, and reputation systems. Nowadays, Cloud computing has several researchers based on blockchain technology for effectively provisioning security and privacy to the Cloud users; still, it lacks to stop the attacks of the outsiders. Integrating Cloud computing and blockchain technology is an emerging paradigm, and the provisioning of security services and network monitoring using incapable distributed techniques or trusted third-party brokers lead to numerous security challenges. In addition, the attacker tries to hack the bitcoin by making various attempts to access the key stored in the system of the users. The integrated technology has to improve its research work for preventing attacks, including selfish mining attacks, block discarding attack and difficulty raising attack, eclipse attack, double spending attack, block withholding attack, and anonymity issues in blockchain Cloud.
