First Flight #17: Dussehra

Summary

Both block.timestamp and block.prevrando can be influenced by miners and are not truly random, miners can control the tiemestamp and may have some knowledge of previous block hashes allowing them to potentially choose exactly the chracteristics they wish for their respective NFTs. Thus manipulating the protocol in an unfair way for compared to normal users.

Vulnerability Details

Vulnerability Details

1. Validators can know ahead of time block.timestamp and block.prevrando and use that to predict when/how to participate in the raffle.

2. Users can manipulate their msg.sender value to result in their addresses being used to generate specific characeristics.

3. Users can revert their increaseValuesOfParticipants if they dont like their NFT chracteristics.

Using on-chain values as a randomness seed is a [well-documented attack vector]

Impact

Assigning this exploit as High impact, due to it effectively ruining hte integrity of the overall protocol. Having the ability to circumvent the implemented randomness results in a very unfair advantage to normal holders of the NFT. Having the ability to create and give your NFT the exact characteristics you want completely defeats the point of the protocol.

Tools Used

Slither and manual analysis.

Recommendations

Consider using Chainlink VRF in place of this logic, chainlink VRF provides a cryptograhpically provable random number. https://docs.chain.link/vrf