First Flight #6: Voting Booth

Summary

Tie voting is possible when quorum is reached.

Vulnerability Details

According to business logic, we check the oddness of voters, most likely this is used to exclude a tie.

But checking the quorum if (totalCurrentVotes * 100 / s_totalAllowedVoters >= MIN_QUORUM) allows you to create a situation with the same number of votes for and against.

For example, with 3 voters, the first votes for, the second against, we get 66 >= 51 and a draw (1 vs 1)

Impact

Business logic violation

Tools Used

Manual checking

Recommendations

We can extend the condition to check the length of the upvotes and downvotes and if they are not equal, end the vote
if (totalCurrentVotes * 100 / s_totalAllowedVoters >= MIN_QUORUM && s_votersFor.length != s_votersAgainst.length)