Magic Number - The Ethernaut - Writeup

Sat, 30 May 2026 00:00:00 +0000

To solve this level, you only need to provide the Ethernaut with a Solver, a contract that responds to whatIsTheMeaningOfLife() with the right 32 byte number.

Easy right? Well… there’s a catch.

The solver’s code needs to be really tiny. Really reaaaaaallly tiny. Like freakin’ really really itty-bitty tiny: 10 bytes at most.

Analysis

The code of the contract is:

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

contract MagicNum {
    address public solver;

    constructor() {}

    function setSolver(address _solver) public {
        solver = _solver;
    }

    /*
    ____________/\\\_______/\\\\\\\\\_____        
     __________/\\\\\_____/\\\///////\\\___       
      ________/\\\/\\\____\///______\//\\\__      
       ______/\\\/\/\\\______________/\\\/___     
        ____/\\\/__\/\\\___________/\\\//_____    
         __/\\\\\\\\\\\\\\\\_____/\\\//________   
          _\///////////\\\//____/\\\/___________  
           ___________\/\\\_____/\\\\\\\\\\\\\\\_ 
            ___________\///_____\///////////////__
    */
}

So, we need to deploy a contract, whose runtime code size is less than or equal to 10 bytes. This contract needs to return 42 when the function whatIsTheMeaningOfLife() gets called on it.

Opcodes on manbolq's Blog

Magic Number - The Ethernaut - Writeup

Analysis