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code423n4Code4renaCODE423N4:2023-12-REVOLUTIONPROTOCOL-FINDINGS-ISSUES-719
HistoryDec 21, 2023 - 12:00 a.m.

Input Validation for _vote Function

2023-12-2100:00:00
Code4rena
github.com
2
input validation
voter
pieceid
security consideration
efficiency
risk reduction
weight requirement
flash attacks

7.2 High

AI Score

Confidence

Low

Lines of code

Vulnerability details

Potential Risk:
The _vote function in the CultureIndex contract takes two parameters: pieceId and voter. While the function includes some input validation checks, there are some potential issues and missing checks that should be addressed.

Proof of Concept (PoC):
Consider a scenario where an attacker attempts to vote for a piece with an invalid pieceId or an invalid voter address:

// Attempt to vote with an invalid pieceId
_vote(MAX_PIECE_ID + 1, msg.sender);

// Attempt to vote with an invalid voter address
_vote(pieceId, address(0));

In these PoC examples, an attacker tries to vote with an out-of-range pieceId and an invalid voter address. The _vote function should have additional checks to prevent such scenarios.

Recommended Mitigation Steps:
To mitigate the risk of using invalid pieceId or voter addresses, consider adding or enhancing input validation checks within the _vote function. Here’s a recommended solution:

function _vote(uint256 pieceId, address voter) internal {
require(pieceId < _currentPieceId, “Invalid piece ID”);
require(voter != address(0), “Invalid voter address”);
require(!pieces[pieceId].isDropped, “Piece has already been dropped”);
require(votes[pieceId][voter].voterAddress == address(0), “Already voted”); // Updated this check
require(_getPastVotes(voter, pieces[pieceId].creationBlock) > minVoteWeight, “Weight must be greater than minVoteWeight”);

uint256 weight = _getPastVotes(voter, pieces[pieceId].creationBlock);

votes[pieceId][voter] = Vote(voter, weight);
totalVoteWeights[pieceId] += weight;

uint256 totalWeight = totalVoteWeights[pieceId];

// TODO add security consideration here based on block created to prevent flash attacks on drops?
maxHeap.updateValue(pieceId, totalWeight);
emit VoteCast(pieceId, voter, weight, totalWeight);

}

In this solution:

  • We’ve enhanced the input validation checks to ensure that the voter has not already voted for the same pieceId before allowing the vote.
  • We’ve also combined the check for the minimum weight requirement into a single require statement for efficiency.
  • These changes help prevent the use of invalid or unexpected input parameters and improve the overall input validation of the _vote function.

By implementing this solution, you can reduce the risk of issues related to invalid input parameters when voting for a piece.

Assessed type

Invalid Validation


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All reactions

7.2 High

AI Score

Confidence

Low