Xend Finance

Xend Finance (XF) is a decentralized Credit Union protocol built to optimize, improve and add value to the core operations of credit unions globally. Xend Finance gives individuals, groups, cooperatives and credit unions in countries with unstable currencies access to a global trustless and stable-currency savings, lending, investing and borrowing network.

Xend Finance has also developed a Layer 2 DeFi infrastructure that automatically seeks out the best yields in DeFi by optimizing and automatically aggregating existing DeFi lending protocols. This infrastructure was designed to maintain high yield with influx of users and capital from traditional finance into decentralized finance as well as provide a better user experience for investors seeking the best yields in DeFi.

Centralized and Fiat savings platforms are always limited by fees and cross-border payment regulations that limit investing in other countries. With Xend Finance, anyone, whether individuals, cooperatives or credit unions, anywhere in the world can save, lend and invest in different DeFi protocols and start earning interests instantly.

For more information about Xend Finance, please visit https://xend.finance.

For connecting with the Xend Finance Dev team: via Telegram: https://t.me/XendFinanceDevs and via Discord: https://discord.gg/QPH2M3nbku.

This bug bounty program is focused on their smart contracts and is focused on preventing:

• Loss of user funds staked by freezing or theft
• Theft of unclaimed yield
• Unable to call smart contract
• Smart contract fails to deliver promised returns
• Temporary freezing of funds
• Loss of governance funds
• Loss of treasury funds

Rewards are distributed according to the impact of the vulnerability based on the Immunefi Vulnerability Severity Classification System. This is a simplified 5-level scale, with separate scales for websites/apps and smart contracts/blockchains, encompassing everything from consequence of exploitation to privilege required to likelihood of a successful exploit.

No PoC is required for smart contract bug reports.

Known issues from their previous audits are considered out-of-scope:

https://omniscia.io/xend-finance-x-vault/static-analysis

https://omniscia.io/xend-finance-polygon-xtokens/static-analysis

https://mega.nz/file/OYUVjAqA#amYLyJOV82MSc5BHqOacoV_zxw9k9P6co35Gdd86iUY

https://mega.nz/file/ad0y3YJS#oVAuekM1uc4VAQc4AeyEleJRBB025QD36CMwShUoTXA

Payouts are handled by the Xend Finance team directly and are denominated in USD. Payouts are done in USDT.

All smart contracts of Xend Finance can be found at https://github.com/xendfinance. However, only those in the Assets in Scope table are considered as in-scope of the bug bounty program.

Impacts in Scope

Only the following impacts are accepted within this bug bounty program. All other impacts are not considered as in-scope, even if they affect something in the assets in scope table.

Smart Contracts/Blockchain

• Loss of user funds staked (principal) by freezing or theft
• Theft of unclaimed yield
• Unable to call smart contract
• Smart contract fails to deliver promised returns
• Temporary freezing of funds for any amount of time
• Loss of governance funds
• Loss of treasury funds

We are especially interested in receiving and rewarding vulnerabilities of the following types:

Smart Contracts and Blockchain

• Re-entrancy
• Logic errors
  • including user authentication errors
• Solidity/EVM details not considered
  • including integer over-/under-flow
  • including rounding errors
  • including unhandled exceptions
• Trusting trust/dependency vulnerabilities
  • including composability vulnerabilities
• Oracle failure/manipulation
• Novel governance attacks
• Economic/financial attacks
  • including flash loan attacks
• Congestion and scalability
  • including running out of gas
  • including block stuffing
  • including susceptibility to frontrunning
• Consensus failures
• Cryptography problems
  • Signature malleability
  • Susceptibility to replay attacks
  • Weak randomness
  • Weak encryption
• Susceptibility to block timestamp manipulation
• Missing access controls / unprotected internal or debugging interfaces

The following vulnerabilities are excluded from the rewards for this bug bounty program:

• Attacks that the reporter has already exploited themselves, leading to damage
• Attacks requiring access to leaked keys/credentials
• Attacks requiring access to privileged addresses (governance, strategist)

Smart Contracts and Blockchain

• Incorrect data supplied by third party oracles
  • Not to exclude oracle manipulation/flash loan attacks
• Basic economic governance attacks (e.g. 51% attack)
• Lack of liquidity
• Best practice critiques
• Sybil attacks

The following activities are prohibited by this bug bounty program:

• Any testing with mainnet or public testnet contracts; all testing should be done on private testnets
• 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
• Automated testing of services that generates significant amounts of traffic
• Public disclosure of an unpatched vulnerability in an embargoed bounty