Due to the immutable nature of the blockchain, smart contracts that have been deployed on the blockchain cannot be changed. In order to improve the security of the contract and prevent the smart contract from integer overflow, short address attacks, pseudo-random, etc., it is necessary that perform vulnerability detection on the contract before the contract have been deployed. This paper analyzed and researched the symbolic execution of the integer overflow vulnerability of the smart contract, and the investigation found that the detection speed of existing symbolic execution methods was slow. Then this paper proposed an improved symbolic execution method for solving constraints from the bottom, which combined depth first and breadth first path selection to improve code coverage of symbolic execution. The experimental results show that the improved symbolic execution has a detection accuracy rate of 84% in the selected 100 smart contracts containing overflow vulnerabilities, and the average detection efficiency has increased by 20%. The detection efficiency in medium-scale smart contracts has increased significantly, and the detection results have a higher accuracy high.

[2021-07-05] Printed Article /doc/2020.10.0353/v2