Beanstalk: The Finale
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Submission Details
Severity: medium
Valid

Incorrect tractor signature schema, should use EIP712_TYPE_HASH when composing the signature

asefewwexa

Line of code

https://github.com/Cyfrin/2024-05-beanstalk-the-finale/blob/df2dd129a878d16d4adc75049179ac0029d9a96b/protocol/contracts/libraries/LibTractor.sol#L24

Summary

tractor signature is not eip 712 compliant

Vulnerability Details

bytes32 private constant EIP712_TYPE_HASH =
keccak256(
"EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"
);

This EIP712_TYPE_HASH is not in the signature schema, then the signature is not EIP 712 complicant,

https://github.com/ethereum/EIPs/blob/master/EIPS/eip-712.md

if we take a look at this line of code

https://github.com/Cyfrin/2024-05-beanstalk-the-finale/blob/df2dd129a878d16d4adc75049179ac0029d9a96b/protocol/contracts/libraries/LibTractor.sol#L177

function _domainSeparatorV4() internal view returns (bytes32) {
return
keccak256(
abi.encode(
BLUEPRINT_TYPE_HASH,
TRACTOR_HASHED_NAME,
TRACTOR_HASHED_VERSION,
C.getChainId(),
address(this)
)
);
}

the BLUEPRINT_TYPE_HASH is used instead of the EIP712_TYPE_HASH

Impact

the signature will not comply with the EIP 712 and the generation is generated incorrectly.

Tools Used

Manual review

Recommendations

EIP712_TYPE_HASH must be in the signature schema to ensure the protocol is eip compliant

here is a reference implementation from openzeppelin

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/05f218fb6617932e56bf5388c3b389c3028a7b73/contracts/utils/cryptography/EIP712.sol#L89

the type hash is

https://github.com/OpenZeppelin/openzeppelin-contracts/blob/05f218fb6617932e56bf5388c3b389c3028a7b73/contracts/utils/cryptography/EIP712.sol#L37

​
bytes32 private constant TYPE_HASH =
keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)");
Updates

Lead Judging Commences

inallhonesty Lead Judge about 1 year ago
Submission Judgement Published
Validated
Assigned finding tags:

Tractor not compliant to EIP712 requirement because it's using the type hash of the blueprint, not the EIP712Domain

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