NFTfi (Testnet Refi)

NFTfi is the leading liquidity protocol for NFTs. NFTfi allows NFT owners to use the assets (NFTs) they own to access the liquidity they need by receiving secured loans from liquidity providers, peer-to-peer, in a completely trustless manner.

For more information about NFTfi, please visit https://www.nftfi.com/

NFTfi provides rewards in USDC, denominated in USD. For more details about the payment process, please view the Rewards by Threat Level section further below.

Refinancing Feature Description

Refinancing is a feature that allows the borrower with an existing loan to refinance to a loan with better terms, using the same collateral.

It works by allowing the borrower with an existing loan to accept any other valid offer on the same collateral. The new offer is typically with a new lender, but could also be with the original lender. Refinancing between different types of loans

The contracts implementing the feature are one layer above the loan contracts and facillitates refinancing of loans between any of the loan contracts. You can refinance

• a "Direct loan" to another "Direct loan"
• a "collection offer loan" to another "collection offer loan"
• a "Direct loan" to a "collection offer loan"
• a "collection offer loan" to another "Direct loan"

Refinancing mechanism

• The refinancing contract takes over the borrowers loan position by taking ownership of the the Obligation Receipt (this requires the borrower to mint the O.R. and approve the Refinancing contract to transfer it)
• The refinancing contract takes out a flashloan from DyDx and pays off the old loan
• The refinancing contract initiates the new loan using the collateral NFT released from the old loan
• Based on the relation of the old loan's principal and the new one's, the Refinancing contract either takes the deficit from the borrower or pays out a surplus (in the deficit-case, the borrower must approve the transfer of the erc20)
• The refinancing contract pays off the flashloan
• The refinancing contract transfers the borrower rights of the new loan by transferring the O.R to the borrower of the original loan

Limitations

Refinancing is only possible if the original and new loan have the same loan denomination.

If the currency of the source loan is not supported by DyDx (e.g. wstETH), we do a 2-way swap on uniswap at the beginning and the end of the process by swapping to WETH.

Responsible Publication

NFTfi adheres to category 3 - Approval Required. This Policy determines what information researchers are allowed to make public from their submitted bug reports. For more information about the category selected, please refer to our Responsible Publication page.

Primacy of Impact vs Primacy of Rules

NFTfi adheres to the Primacy of Rules, which means that the whole bug bounty program is run strictly under the terms and conditions stated within this page.

Proof of Concept (PoC) Requirements

A PoC, demonstrating the bug's impact, is required for this program and has to comply with the Immunefi PoC Guidelines and Rules.

Known Issue Assurance

NFTfi commits to providing Known Issue Assurance to bug submissions through their program. This means that NFTfi will either disclose known issues publicly, or at the very least, privately via a self-reported bug submission.

In a potential scenario of a mediation, this allows for a more objective and streamlined process, in order to prove that an issue is known. Otherwise, assuming the bug report is valid, it would result in the report being considered as in-scope, and due a reward.

Previous Audits

NFTfi’s completed audit reports can be found at

• First Refinancing audit - https://drive.google.com/file/d/1hTW5eRUiklZg1_2Xo8zvYUSS-FHxD49r
• Second Refinancing audit (with added functionality) - https://drive.google.com/file/d/1SnmYjH-0OYP6Wbu9F5jMb19dD9Mf2ixu
• Third Refinancing audit (with added functionality) - https://drive.google.com/file/d/1HmKuN25_TYRWGAV9wn07OPK-sOYUKObg
• Also relevant to this codebase: USDC blacklist vulnerability - https://drive.google.com/file/d/1vSJ86Ev51sJ56xtU5OZcZ_spgWidiacm

Any unfixed vulnerabilities mentioned in these reports are not eligible for a reward.

Feasibility Limitations

The project may be receiving reports that are valid (the bug and attack vector are real) and cite assets and impacts that are in scope, but there may be obstacles or barriers to executing the attack in the real world. In other words, there is a question about how feasible the attack really is. Conversely, there may also be mitigation measures that projects can take to prevent the impact of the bug, which are not feasible or would require unconventional action and hence, should not be used as reasons for downgrading a bug's severity.

Therefore, Immunefi has developed a set of feasibility limitation standards which by default states what security researchers, as well as projects, can or cannot cite when reviewing a bug report.

Immunefi Standard Badge

By adhering to Immunefi’s best practice recommendations, NFTfi has satisfied the requirements for the Immunefi Standard Badge.

Rewards are distributed according to the impact of the vulnerability based on the Immunefi Vulnerability Severity Classification System V2.3.

Reward Calculation for Critical Level Reports

For critical smart contract bugs on testnet assets, the reward is paid as a flat amount of USD 20 000. This is because there are no actual funds at risk on the testnet, hence limits objective calculation.

Repeatable Attack Limitations

If the smart contract where the vulnerability exists can be upgraded or paused, only the initial attack will be considered for a reward. This is because the project can mitigate the risk of further exploitation by upgrading or pausing the component where the vulnerability exists. The reward amount will depend on the severity of the impact.

Reward Payment Terms

Payouts are handled by the NFTfi team directly and are denominated in USD. However, payments are done in USDC.

The calculation of the net amount rewarded is based on the average price between CoinMarketCap.com and CoinGecko.com at the time the bug report was submitted. No adjustments are made based on liquidity availability.

Documentation and further resources can be found on https://docs.nftfi.com/overview/introduction.

Impacts that depend on NFTfi registering faulty NFT Adapters, Refinancing adapters, NFT collections or ERC20 loan denominations are out of scope. That is, only impacts in the scope of currently registered and enabled adapters, NFT collections and loan denominations.

These impacts are out of scope for this bug bounty program.

All Categories:

• Impacts requiring attacks that the reporter has already exploited themselves, leading to damage
• Impacts caused by attacks requiring access to leaked keys/credentials
• Impacts caused by attacks requiring access to privileged addresses (governance, strategist) except in such cases where the contracts are intended to have no privileged access to functions that make the attack possible
• Impacts relying on attacks involving the depegging of an external stablecoin where the attacker does not directly cause the depegging due to a bug in code
• Mentions of secrets, access tokens, API keys, private keys, etc. in Github will be considered out of scope without proof that they are in-use in production
• Best practice recommendations
• Feature requests
• Impacts on test files and configuration files unless stated otherwise in the bug bounty program

Blockchain/DLT & Smart Contract Specific:

• Incorrect data supplied by third party oracles
  • Not to exclude oracle manipulation/flash loan attacks
• Impacts requiring basic economic and governance attacks (e.g. 51% attack)
• Lack of liquidity impacts
• Impacts from Sybil attacks
• Impacts involving centralization risks

Prohibited Activities:

• Any testing on mainnet or public testnet deployed code; all testing should be done on local-forks of either public testnet or mainnet
• Any testing with pricing oracles or third-party smart contracts
• Attempting phishing or other social engineering attacks against our employees and/or customers
• Any testing with third-party systems and applications (e.g. browser extensions) as well as websites (e.g. SSO providers, advertising networks)
• Any denial of service attacks that are executed against project assets
• Automated testing of services that generates significant amounts of traffic
• Public disclosure of an unpatched vulnerability in an embargoed bounty