Manual Audit for BitUnits Contracts

In the blockchain 2.0 era, smart contracts based on blockchain technology have been widely used in many fields such as sharing economy, digital payment, and financial asset disposal because of its dispersion, observability, verifiability and automatic execution. With the widespread application of smart contracts, the researchers gradually found many types of security problems, so the audit of smart contracts has become the vital way to ensure its security. This paper introduces the implementation mechanism of smart contract model, and summarizes 11 kinds of high frequency smart contract vulnerabilities, such as transaction order dependence, constructor out of control, denial of service, etc. Then, this paper selects the newly released BitUnits contract for auditing, find out its security hole and give the solution.