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

[H-2] Malicious Owner Can Frontrun Whale Claim to Steal Entire Deposit via 100% Platform Fee

wolf_kalp

Root +Impact

[H-2] Malicious Owner Can Frontrun Whale Claim to Steal Entire Deposit via 100% Platform Fee

Description

The updatePlatformFeePercentage(uint256) function allows the onlyOwner to arbitrarily change the platform
fee to any value up to 100%. This fee is applied immediately in the claimThrone() function. A malicious owner
can frontrun high-value claimThrone() transactions by first setting platformFeePercentage = 100, causing the
entire ETH deposit from the next user to be siphoned as platform fees instead of contributing to the prize
pot.

This issue highlights the centralized and overpowered nature of the contract owner, who has unilateral control over multiple critical parameters without any timelock or access mitigation.

Impact:

1.Complete theft of user funds (e.g., if a whale sends 1000 ETH, the owner can steal all of it via 100% platform fee).

2.Undermines game fairness and trust, allowing owner to exploit participants.

3.Unilateral control creates a centralization risk, making the protocol non-trustless.

4.Other functions where the owner can abuse power:

:resetGame() → Owner can restart rounds arbitrarily.
​
:updateClaimFeeParameters() → Can manipulate fees to trap users.
​
:updateGracePeriod() → Can make the game unwinnable.
​
:withdrawPlatformFees() → Can drain all ETH collected via unfair fees.
​
:updatePlatformFeePercentage() → Can legally steal deposits.

Proof of Concept

1.Whale prepares a claimThrone() tx with 1000 ETH.
​
2.Owner monitors mempool, and before whale’s tx confirms:
​
3.game.updatePlatformFeePercentage(100); // Sets 100% platform fee
Whale’s tx confirms and entire 1000 ETH is added to platformFeesBalance, not pot.
​
4.Owner calls:
​
game.withdrawPlatformFees();
Owner steals all 1000 ETH, leaving nothing for the pot or game.
​

Recommended Mitigation

Add Upper Bound to Platform Fee:

Enforce a maximum platform fee cap (e.g., 10%) in the modifier:

require(_percentage <= 10, "Platform fee too high");
​
Updates

Appeal created

inallhonesty Lead Judge 4 months ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity

Support

FAQs

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

Give us feedback!