Last Man Standing
First Flight #45
Beginner FriendlyFoundrySolidity
100 EXP
View results
Previous Next
Submission Details
Impact: high
Likelihood: high
Invalid

Missing Game-Ended Modifier Check missing in updateGracePeriod() Enables Mid-Game Parameter Tampering

eagerpanda582

Root + Impact

Description

  • The updateGracePeriod() function allows the owner to change the gracePeriod even while a game round is active. This can be exploited to extend or shorten the current king's reign, impacting gameplay fairness and user trust.

Risk

Likelihood:

  • The function is callable by the owner at any time. No guard (e.g., gameEndedOnly check) is in place to prevent misuse during active rounds.

Impact:

  • Changing the grace period mid-game can:

    1. Prevent the rightful king from winning.

    2. Enable malicious manipulation by the owner.

    3. Break user trust and violate expectations of fairness and finality.

Proof of Concept

The POC demonstarate that if the owner changes the graceperiod midGame, enabling the currentKing to win.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
​
import {Test, console2} from "forge-std/Test.sol";
import {Game} from "../src/Game.sol";
​
contract GameTest is Test {
Game public game;
​
address public deployer;
address public player1;
​
// Initial game parameters for testing
uint256 public constant INITIAL_CLAIM_FEE = 0.1 ether; // 0.1 ETH
uint256 public constant GRACE_PERIOD = 1 days; // 1 day in seconds
uint256 public constant FEE_INCREASE_PERCENTAGE = 10; // 10%
uint256 public constant PLATFORM_FEE_PERCENTAGE = 5; // 5%
​
function setUp() public {
deployer = makeAddr("deployer");
player1 = makeAddr("player1");
​
vm.deal(deployer, 10 ether);
vm.deal(player1, 10 ether);
​
vm.prank(deployer);
game = new Game(
INITIAL_CLAIM_FEE,
GRACE_PERIOD,
FEE_INCREASE_PERCENTAGE,
PLATFORM_FEE_PERCENTAGE
);
}
​
function test_claimmthrone() external{
vm.prank(player1);
game.claimThrone{value: 1 ether}();
​
vm.prank(deployer);
game.updateGracePeriod(80);
vm.warp(1000);
​
vm.prank(player1);
game.declareWinner();
assertEq(game.currentKing(), player1);
​
​
}
}

Recommended Mitigation

By adding the modifier gameEndedOnly can prevent the owner to change the gracePeriod midgame, thereby mitigating the vulnerability.

  1. Here if we do not add the modifier also it will automatically rest for next round.

  2. And the other option we have to add modifier.

function updateGracePeriod(uint256 _newGracePeriod) external onlyOwner {
require(_newGracePeriod > 0, "Game: New grace period must be greater than zero.");
- gracePeriod = _newGracePeriod;
+ initalGracePeriod = _newGracePeriod;
emit GracePeriodUpdated(_newGracePeriod);
}
- function updateGracePeriod(uint256 _newGracePeriod) external onlyOwner
+ function updateGracePeriod(uint256 _newGracePeriod) external gameEndedOnly onlyOwner
Updates

Appeal created

inallhonesty Lead Judge about 1 month ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity

Support

FAQs

Can't find an answer? Chat with us on Discord, Twitter or Linkedin.