To solve this level, you only need to provide the Ethernaut with a Solver, a contract that responds to whatIsTheMeaningOfLife() with the right 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 opcodes at most.
Hint: Perhaps its time to leave the comfort of the Solidity compiler momentarily, and build this one by hand O_o. That's right: Raw EVM bytecode.
Good luck!
Level Contract
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract MagicNum {
address public solver;
constructor() {}
function setSolver(address _solver) public {
solver = _solver;
}
/*
____________/\\\_______/\\\\\\\\\_____
__________/\\\\\_____/\\\///////\\\___
________/\\\/\\\____\///______\//\\\__
______/\\\/\/\\\______________/\\\/___
____/\\\/__\/\\\___________/\\\//_____
__/\\\\\\\\\\\\\\\\_____/\\\//________
_\///////////\\\//____/\\\/___________
___________\/\\\_____/\\\\\\\\\\\\\\\_
___________\///_____\///////////////__
*/
}
Exploit
make anvil-exploit-level-18
<INPUT_LEVEL_INSTANCE_CONTRACT_ADDRESS>
make holesky-exploit-level-18
<INPUT_LEVEL_INSTANCE_CONTRACT_ADDRESS>
script/Level18.s.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import {Script, console} from "forge-std/Script.sol";
import {HelperFunctions} from "script/HelperFunctions.s.sol";
// ================================================================
// │ LEVEL 18 - MAGIC NUMBER │
// ================================================================
interface IMagicNum {
function setSolver(address _solver) external;
}
contract Exploit is Script, HelperFunctions {
function run() public {
address targetContractAddress = getInstanceAddress();
vm.startBroadcast();
// Store the contract bytecode
bytes memory bytecode = hex"600a600c600039600a6000f3602a60505260206050f3";
// Deploy the contract using create
address deployedAddress;
assembly {
deployedAddress := create(0, add(bytecode, 0x20), mload(bytecode))
}
// Set the solver address
IMagicNum(targetContractAddress).setSolver(address(deployedAddress));
vm.stopBroadcast();
}
}
Submit instance... 🥳
Completion Message
Congratulations! If you solved this level, consider yourself a Master of the Universe.
Go ahead and pierce a random object in the room with your Magnum look. Now, try to move it from afar; Your telekinesis abilities might have just started working.
