Always handle return value from functions enterMarket() and exitMarket() of Compound V2.
if market is not listed it will return MARKET_NOT_LISTED error. Every external call to other protocol should be reviewed and handled.@EthSecurity1

The "1 Wei Attack" is an exploitation of some DeFi platforms' vaults or liquidity pools, specifically those employing AMMs.

This attack takes advantage of the lack of slippage protection which leads to asset dilution and potential loss of funds for unsuspecting users. Suppose the following occurred:

1. The vault is empty
2. Alice deposits 1 token (1e18 units) into vault
3. Bob front-runs it, depositing 1 unit
4. Bob donates 1 token (1e18 units) into the vault using ERC20 transfer
5. Alice's deposit is executed

What happens?With an empty vault, the shares are being minted at a 1:1 rate with the amount. After Bob deposits 1 unit, the rate is 1:1 unit:shares.

Then, Bob donates another 1e18 units. This will make totalAssets = 1e18 + 1.Finally, Alice's transaction is completed and she gets:

(1e18*1) / (1e18 + 1) = 0.99999.. shares

In solidity, the decimals are truncated, and she gets 0 shares! 😲
@EthSecurity1

In delegate call msg.sender can be altered @EthSecurity1