FixedDonation.sol

// SPDX-License-Identifier: BSL-1.0 (Boost Software License 1.0)

//-------------------------------------------------------------------------------------//
// Copyright (c) 2022 - 2023 serial-coder: Phuwanai Thummavet (mr.thummavet@gmail.com) //
//-------------------------------------------------------------------------------------//

// For more info, please refer to my article:
//  - On Medium: https://medium.com/valixconsulting/solidity-smart-contract-security-by-example-07-phishing-with-improper-authorization-232dacf307e3
//  - On serial-coder.com: https://www.serial-coder.com/post/solidity-smart-contract-security-by-example-07-phishing-with-improper-authorization/

pragma solidity 0.8.17;

contract FixedDonation {
    address public immutable owner;

    constructor() {
        owner = msg.sender;
    }

    function buyMeACoffee() external payable {
    }

    function getBalance() external view returns (uint256) {
        return address(this).balance;
    }

    function collectEthers(address payable _to, uint256 _amount) external {
        require(msg.sender == owner, "Not owner");  // FIX: Use msg.sender instead of tx.origin

        (bool success, ) = _to.call{value: _amount}("");
        require(success, "Failed to send Ether");
    }
}