Beosin: There is a loophole in the business logic of the sDAO contract, and the attacker made more than 13,000 BUSD in profit

According to the Beosin EagleEye security risk monitoring, early warning and blocking platform monitoring of the blockchain security audit company Beosin, the sDAO project on the BNB Chain has suffered a vulnerability attack. Beosin analysis found that there is an error in the business logic of the sDAO contract. The getReward function is calculated based on the LP tokens owned by the contract and the LP tokens added by the user as parameters. The total number of LP tokens is negatively correlated, but the contract provides a withdrawTeam method, which can send all the BNB and specified tokens owned by the contract to the specified address of the contract. This function can be called by anyone. This time, after the attacker added LP tokens to it, he called the withdrawTeam function to send all LP tokens to the specified address, and immediately transferred a very small amount of LP tokens to the contract, causing the attacker to call When getReward obtains rewards, the total number of LP tokens in the contract used is a very small value, which makes the rewards magnified abnormally. In the end, the attacker made a profit of about 13662 BUSD through this vulnerability.