/ethereum_sandbox.sol Secret
Last active
February 26, 2019 03:52
Star
You must be signed in to star a gist
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
pragma solidity ^0.5.0; | |
contract Vulnerable { | |
uint256[] public writes; | |
address[] public owners; | |
constructor() public payable { | |
owners.push(msg.sender); | |
writes.length -= 1; | |
} | |
function write_what_where_gadget(uint256 _what, uint256 _where) public { | |
writes[_where] = _what; | |
} | |
function fun_sandbox(address _addr) public payable { | |
bool taint = false; | |
for(uint256 i = 0; i < owners.length; i++) { | |
if(msg.sender == owners[i]) { | |
taint = true; | |
} | |
} | |
require(taint); | |
uint256 size; | |
bytes memory code; | |
assembly { | |
size := extcodesize(_addr) | |
code := mload(0x40) | |
mstore(0x40, add(code, and(add(add(size, 0x20), 0x1f), not(0x1f)))) | |
mstore(code, size) | |
extcodecopy(_addr, add(code, 0x20), 0, size) | |
} | |
for(uint256 i = 0; i < code.length; i++) { | |
require(code[i] != 0xf0); // CREATE | |
require(code[i] != 0xf1); // CALL | |
require(code[i] != 0xf2); // CALLCODE | |
require(code[i] != 0xf4); // DELEGATECALL | |
require(code[i] != 0xfa); // STATICCALL | |
require(code[i] != 0xff); // SELFDESTRUCT | |
} | |
bool success; | |
bytes memory _; | |
(success, _) = _addr.delegatecall(""); | |
require(success); | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment