Recovery - The Ethernaut - Writeup

Fri, 29 May 2026 00:00:00 +0000

A contract creator has built a very simple token factory contract. Anyone can create new tokens with ease. After deploying the first token contract, the creator sent 0.001 ether to obtain more tokens. They have since lost the contract address.

This level will be completed if you can recover (or remove) the 0.001 ether from the lost contract address.

This is the code of the contract:

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

contract Recovery {
    //generate tokens
    function generateToken(string memory _name, uint256 _initialSupply) public {
        new SimpleToken(_name, msg.sender, _initialSupply);
    }
}

contract SimpleToken {
    string public name;
    mapping(address => uint256) public balances;

    // constructor
    constructor(string memory _name, address _creator, uint256 _initialSupply) {
        name = _name;
        balances[_creator] = _initialSupply;
    }

    // collect ether in return for tokens
    receive() external payable {
        balances[msg.sender] = msg.value * 10;
    }

    // allow transfers of tokens
    function transfer(address _to, uint256 _amount) public {
        require(balances[msg.sender] >= _amount);
        balances[msg.sender] = balances[msg.sender] - _amount;
        balances[_to] = _amount;
    }

    // clean up after ourselves
    function destroy(address payable _to) public {
        selfdestruct(_to);
    }
}

The challenge deployes a Recovery contract and gives us its address. This contract deployes a SimpleToken contract when it is called. Because of the challenge description, we assume that the challenge called the generateToken function, sent 0.001 ether to the contract created and lost the address.

Contract Address on manbolq's Blog

Recovery - The Ethernaut - Writeup