Summary

ThePredicter::withdrawPredictionFees function calculates and executes the withdrawal of rewards to players that have positive points. However there is an incorrect calculation because this function assumes that the contract balance, address(this).balance - players.length * entrance fee = player prediction fee to be withdrawn.

Vulnerability Details

uint256 fees = address(this).balance - players.length * entranceFee;

Impact

If the players.length * entrance fee is more than the address(this).balance, this would cause an calculation error. This can drain the procol of funds and also deny some players their due prediction fee. Also if the players.length * entranceFee is more than the contract account balance address(this).balance there would be negative fee to withdraw which is an error in the protocol.

Tools Used

manual review

Recommendations

The correct parameter should be implemented to calculate the prediction fee. The correct parameter of how the protocol's prediction fee calculation should be documented and implemented. Ensure the calculation accurately reflects the intended fee structure based on the documentation. Also add checks to ensure the balance is sufficient before performing the calculation.