Core Contracts

Summary

The function getNFTPrice() can be DoS by destroying the house in real life so that the value return by Oracle is 0. This can happen intentionally or by natural disaster

A DoS of getNFTPrice() will protect the user from liquidation, as it's called in initiateLiquidation()->calculateHealthFactor()->getUserCollateralValue(). It will cause a revert of initiateLiquidation

Vulnerability Details

The function getNFTPrice() will revert if the oracle returns 0. There are some cases when it's possible and it will prevent the user from entering into liquidation, incurring bad debt into the protocol.

1. UserA deposit NFTs of houseA, houseB, houseC

2. UserA borrows amounts against NFTs

3. HouseA is either destroyed intentionally (the user discovers issues with houses that will make the price drop a lot) or a natural disaster happens and totally destroys the house.

4. UserA cannot enter liquidation state as initiateLiquidation() will revert because oracle return 0 on getNFTPrice()

Impact

Users cannot be liquidated, incurring bad debt to the protocol. If the user has only one NFT it does not change much as the value is 0, but if the user has multiple NFTs on the protocol, it's impossible to get them back to mitigate the bad debt. NFTs would be stuck forever in the LendingPool, incurring loss for the protocol.

Tools Used

Manual

Recommendations

Change how strange values are handled by the Oracle. Inthe case of a natural disaster, there is a high probability that manual intervention would be required.