Insomni Hack 2023 - NotSuchSolidIT challenge
2023, Nov 08
This article presents the challenge NotSuchSolidIT from Insomni’hack
Contracts
The challenge was formed of two different files :
- setup.sol
- Challenge.sol
Two smartcontracts have been deployed, try to withdrawal the Challenge.sol to get the flag.
Setup.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.1;
import "./Challenge.sol";
contract Setup {
Challenge public chall;
constructor() payable {
require(msg.value >= 100, "Not enough ETH to create the challenge..");
chall = (new Challenge){ value: 50 ether }();
}
function isSolved() public view returns (bool) {
return address(chall).balance == 0;
}
function isAlive(string calldata signature, bytes calldata parameters, address addr) external returns(bytes memory) {
(bool success, bytes memory data) = address(addr).call(
abi.encodeWithSelector(
bytes4(keccak256(bytes(signature))),
parameters
)
);
require(success, 'Call failed');
return data;
}
}
Challenge
// SPDX-License-Identifier: UNLICENSED
pragma solidity 0.8.1;
contract Challenge {
address payable owner;
constructor() payable {
owner = payable(msg.sender);
}
modifier onlyOwner {
require(msg.sender == owner);
_;
}
function getBalance() public view returns (uint){
return address(this).balance;
}
function withdrawAll(address payable _to) public onlyOwner {
_to.transfer(address(this).balance);
}
function destroy() public onlyOwner {
selfdestruct(owner);
}
}
Solution
1.Compile the contracts with Remix: https://remix.ethereum.org
2.Connect with a custom external provider
3.Call withdrawAll with the parameters
4.Check if the challenge isSolved
