The Vault contract and the modules contracts should not receive ETH

[code423n4]

Lines of code

https://github.com/code-423n4/2022-07-fractional/blob/8f2697ae727c60c93ea47276f8fa128369abfe51/src/Vault.sol#L32
https://github.com/code-423n4/2022-07-fractional/blob/8f2697ae727c60c93ea47276f8fa128369abfe51/src/modules/Buyout.sol#L53
https://github.com/code-423n4/2022-07-fractional/blob/8f2697ae727c60c93ea47276f8fa128369abfe51/src/modules/Migration.sol#L63

Vulnerability details

Impact

If this contracts receive eth and this eth could get stuck in the contract

Proof of Concept

• receive() external payable {}
• receive() external payable {}
• receive() external payable {}

Tools Used

Manual Review

Recommended Mitigation Steps

Remove the receive function of Vault contract and modules contracts:

• Vault.sol#L32
• modules/Buyout.sol#L53
• modules/Migration.sol#L63

[HardlyDifficult]

This seems to be required for Migration. But the test suite passes with the others removed. Since this is about protecting against user error, lowing sev and merging with the warden's QA report #554