  With the more and more extensive application of blockchain, blockchain
security has been widely concerned by the society and deeply studied by
scholars. Moreover, the security of blockchain data directly affects the
security of various applications of blockchain. In this survey, we perform a
comprehensive classification and summary of the security of blockchain data.
First, we present classification of blockchain data attacks. Subsequently, we
present the attacks and defenses of blockchain data in terms of privacy,
availability, integrity and controllability. Data privacy attacks present data
leakage or data obtained by attackers through analysis. Data availability
attacks present abnormal or incorrect access to blockchain data. Data integrity
attacks present blockchain data being tampered. Data controllability attacks
present blockchain data accidentally manipulated by smart contract
vulnerability. Finally, we present several important open research directions
to identify follow-up studies in this area.
