Solution.md

Fallout

The goal of this level is to claim ownership of Fallout.sol. The only place this contract sets the owner is within its constructor. Prior to Solidity 0.4.22, constructors were defined as functions that carried the same name as the contract. So the constructor for contract HelloWorld would be HelloWorld().

The issue with this naming convention is that it is prone to human error - developers can accidentally misspell the constructor name, or forget to update it when contracts are renamed. Take a closer look at Fallout.sol's constructor function:

function Fal1out() public payable {
        owner = msg.sender;
        allocations[owner] = msg.value;
}

The name of the constructor is misspelled, which means that it is just another function with a public visibility. This means that any external user or function inside the contract can call this function. Thus, whoever calls Fal1out() becomes the owner of the contract.

Remix Users

If you are trying to complete these levels within Remix, you can't always copy/paste the contract code and deploy it as is. If you try copy-pasting you'll be met with the following error: Error: not found openzeppelin-contracts-06/math/SafeMath.sol. An easy way to circumvent this would be to code a contract like so:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

interface Fallout {
    function Fal1out() external payable;
}

Here, you can deploy the contract at the provided address and call Fal1out() in order to complete the level.