Attacker can block the payment and refund of funds in the auction.

[c4-submissions]

Lines of code

https://github.com/code-423n4/2023-10-nextgen/blob/8b518196629faa37eae39736837b24926fd3c07c/smart-contracts/AuctionDemo.sol#L104-L120

Vulnerability details

Impact

If the highest bidder's address in the auction belongs to a contract that does not implement the onERC721Received() function, calling claimAuction() becomes impossible. Consequently, the remaining funds from bids become trapped in the auction contract. This vulnerability can be exploited by an attacker who deliberately uses a contract without implementing the required function and aims to become the highest bidder, thereby blocking the refund process.

Proof of Concept

Suppose an attacker employs a contract that does not implements onERC721Received() to call AuctionDemo::participateToAuction() and manage to bid high enough to become the highest bidder. In this scenario when the AuctionDemo::claimAuction() function is invoked to process the token transfer and refund remaining active bids, the call will revert due to the use of safeTransferFrom(). It's important to note that this scenario can also occur unintentionally if the highest bidder's address is a contract that lacks the required ERC721Receiver functionality.

Since the auction has ended (block.timestamp <= minter.getAuctionEndTime(_tokenId)), and there is no alternative method for bidders to retrieve their funds (as cancelBid and cancelAllBids are disabled when auctions ends), the token and all funds become permanently trapped within the contract. Thefore this issue is classified as high severity, as any attacker can exploit this vulnerability intentionally, effectively freezing all funds in the contract.

Tools Used

Manual Review.

Recommended Mitigation Steps

Consider using transferFrom() instead of safeTransferFrom().

Assessed type

ERC721

[c4-pre-sort]

141345 marked the issue as duplicate of #364

[c4-pre-sort]

141345 marked the issue as not a duplicate

[c4-pre-sort]

141345 marked the issue as duplicate of #1653

[c4-pre-sort]

141345 marked the issue as duplicate of #843

[c4-pre-sort]

141345 marked the issue as duplicate of #486

[c4-judge]

alex-ppg marked the issue as not a duplicate

[c4-judge]

alex-ppg marked the issue as duplicate of #1759

[c4-judge]

alex-ppg marked the issue as partial-50

[c4-judge]

alex-ppg changed the severity to 2 (Med Risk)