Raisebox Faucet
First Flight #50
Beginner FriendlySolidity
100 EXP
View results
Previous Next
Submission Details
Severity: low
Valid

Faucet Token Claim Blocked When Contract Balance Equals FaucetDrip

0xnigthswatch

Root + Impact

Description

  • The contract currently prevents a user from claiming faucet tokens if the contract balance is less than or equal to the per-claim amount (faucetDrip):

if (balanceOf(address(this)) <= faucetDrip) {
@> revert RaiseBoxFaucet_InsufficientContractBalance();
}
​

  • This logic blocks claims even when there are enough tokens in the contract to fulfill exactly one claim.

  • Intended behavior: users should be able to claim tokens as long as the contract has at least faucetDrip tokens, without unnecessarily blocking claims.

Risk

Likelihood:

  • Triggered whenever the contract balance is equal to the per-claim faucet token amount.

Impact:

  • Users are prevented from claiming available tokens, potentially leaving small balances stranded in the contract.


Reduces usability and can frustrate users expecting to receive any available tokens.

Proof of Concept

In the following POC, the faucet total supply of tokens will be set through burn and mint fucntion to exactly faucetDrip, then a user will claim it but the claim will revert although there is enough tokens to fulfill this claim.

function test_claimFaucetTokens_blocked_when_contract_has_exactly_faucetDrip()
public
{
// drain all fauct tokens by calling burnFaucetTokens()
vm.prank(owner);
raiseBoxFaucet.burnFaucetTokens(
raiseBoxFaucet.balanceOf(address(raiseBoxFaucet))
);
// assert the faucet has no more tokens
assertEq(raiseBoxFaucet.balanceOf(address(raiseBoxFaucet)), 0);
// now mint to the faucet exactly faucetDrip
vm.prank(owner);
raiseBoxFaucet.mintFaucetTokens(
address(raiseBoxFaucet),
raiseBoxFaucet.faucetDrip()
);
assertEq(
raiseBoxFaucet.balanceOf(address(raiseBoxFaucet)),
raiseBoxFaucet.faucetDrip()
);
​
// if any user attempt to claim the faucetDrip, it will revert also the faucetDrip amount is present
vm.expectRevert();
vm.prank(user1);
raiseBoxFaucet.claimFaucetTokens();
}

Recommended Mitigation

In this fix, the fucntion will revert only if the contract has less than faucetDrip otherwise the fucntion will go through.

- if (balanceOf(address(this)) <= faucetDrip) {
+ if (balanceOf(address(this)) < faucetDrip) {}
revert RaiseBoxFaucet_InsufficientContractBalance();
}
Updates

Lead Judging Commences

inallhonesty Lead Judge 9 days ago
Submission Judgement Published
Validated
Assigned finding tags:

Off-by-one error in `claimFaucetTokens` prevents claiming when the balance is exactly equal to faucetDrip

Support

FAQs

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