DEALS——Track Token Transfer Information Inconsistency

Blockchain enables traditional exchanges and lending houses to be extended to Depl (decentralized platforms), which allows anyone to access exchange and lending without the help of intermediaries. Most Depls are implemented as smart contracts running on Ethereum and interact with another smart contract, cryptocurrency (i.e. token), to achieve various functions. Although Depl involves more than 35 billion worth of tokens, little is known about whether the actual transfer of tokens is as consistent as Depl expects. The inconsistency between the actual transfer of tokens and what the decentralized platform expects is known as behavioral inconsistency, resulting in property damage and user confusion. In this work, we take the first step to investigate such inconsistency between Depl and tokens. We propose to automatically detect inconsistency by comparing the actual token transfer behavior with the behavior indicated by the internal records of Depl by monitoring the core data structure changes of Depl and token.The experimental results show that inconsistent behavior exists in 1012749 transactions with an accuracy of 98.0%, which involves 2871 pairs of Depl and tokens, and is related to 110 Depl and 2544 tokens.In addition, 10 main reasons behind the inconsistency are summarized, e.g., cheater Depl, inconsistent scale, unclear coin lock rules, etc.