instead of call() , transfer() is used to withdraw the ether

[code423n4]

Handle

JMukesh

Vulnerability details

Impact

function withdraw(uint amount) external {
require(amount <= ethBalance[msg.sender]);
ethBalance[msg.sender] = ethBalance[msg.sender].sub(amount);
msg.sender.transfer(amount);
emit Withdraw(msg.sender, amount);
}

To withdraw eth it uses transfer(), this trnansaction will fail inevitably when : -

1. The withdrwer smart contract does not implement a payable function.

2. Withdrawer smart contract does implement a payable fallback which uses more than 2300 gas unit

3. Thw withdrawer smart contract implements a payable fallback function whicn needs less than 2300 gas unit but is called through proxy that raise the call's gas usage above 2300

https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/

Proof of Concept

https://github.com/code-423n4/2021-04-redacted/blob/main/Beebots.sol#L649

Tools Used

no tool used

Recommended Mitigation Steps

use call() to send eth