Fjord Token Staking

##Summary

The bid function is susceptible to front-running attacks because the bid amount is visible in the mempool before the transaction is confirmed. A malicious bidder can exploit this by monitoring the mempool and submitting a higher bid with a higher gas fee to outbid others unfairly.

##Vulnerability Details

1. Place a bid using the bid function.

2. Monitor the mempool for pending transactions.

3. Submit a higher bid with a higher gas fee before the initial bid is confirmed.

   Let's look in a scenerio where by a genuine-bidder places a bid of 200 FjordPoints, A malicious bidder can observe this bid and submit a higher bid of 250 FjordPoints with a higher gas fee before A genuine-bidder's bid is confirmed, thereby winning the auction unfairly.

4. https://github.com/Cyfrin/2024-08-fjord/blob/0312fa9dca29fa7ed9fc432fdcd05545b736575d/src/FjordAuction.sol#L143

##Impact

A Malicious bidder can observe pending bids and submit higher bids with higher gas fees, winning the auction unfairly.

##Tools Used

Manual

##Recommendations

Implement a commit-reveal scheme to hide bid amounts during the bidding phase. Bidders should first commit to a bid via a hash and reveal their bids after the commit phase ends.