00-basic.sol

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.13;


contract Vulnerable {

    mapping (address => uint256) balance;
	mapping (address => bool) vip;
	
    
    function deposit() external payable {
        balance[msg.sender] += msg.value;
    }
	

	function withdrawAll() external {		
		// Checks!
		require(balance[msg.sender] > 0, "Not enough funds");	
		// Interactions D: VULNERABLE!!
		(bool success, ) = payable(msg.sender).call{value: balance[msg.sender]}("");
		require(success, "Low level call failed");
		// Effects :(
		balance[msg.sender] = 0;	
	}

	function withdrawSome(uint256 amount) external {		
		// Checks!
		require(balance[msg.sender] >= amount, "Not enough funds");	
		// Interactions D: VULNERABLE!!... but exploitable?
		(bool success, ) = payable(msg.sender).call{value: balance[msg.sender]}("");
		require(success, "Low level call failed");
		// Effects :(
		balance[msg.sender] -= amount;	
	}

	
	function userBalance (address _user) public view returns (uint256) {
		return balance[_user];
	}

}