Beanstalk: The Finale
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Submission Details
Severity: high
Invalid

TokenFacet.sol Failure to comply with the EIP-2612

kwakudr

Summary

TokenFacet.sol Failure to comply with the EIP-2612 could lead to reverts

Vulnerability Details

function permitToken(
address owner,
address spender,
address token,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) external payable fundsSafu noNetFlow noSupplyChange nonReentrant {
LibTokenPermit.permit(owner, spender, token, value, deadline, v, r, s);
LibTokenApprove.approve(owner, spender, IERC20(token), value);
}

https://github.com/Cyfrin/2024-05-beanstalk-the-finale/blob/4e0ad0b964f74a1b4880114f4dd5b339bc69cd3e/protocol/contracts/beanstalk/farm/TokenFacet.sol#L154C5-L166C6

According to Eip2612 Doc: Compliant contracts must implement 3 new functions in addition to EIP-20: function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external function nonces(address owner) external view returns (uint) function DOMAIN_SEPARATOR() external view returns (bytes32)

The DOMAIN_SEPARATOR should be unique to the contract and chain to prevent replay attacks from other domains.

https://eips.ethereum.org/EIPS/eip-2612

Compliant contracts must implement 3 new functions in addition to EIP-20:

function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external
function nonces(address owner) external view returns (uint)
function DOMAIN_SEPARATOR() external view returns (bytes32)
​

The semantics of which are as follows:

For all addresses owner, spender, uint256s value, deadline and nonce, uint8 v, bytes32 r and s, a call to permit(owner, spender, value, deadline, v, r, s) will set allowance[owner][spender] to value, increment nonces[owner] by 1, and emit a corresponding Approval event, if and only if the following conditions are met:

  • The current blocktime is less than or equal to deadline.

  • owner is not the zero address.

  • nonces[owner] (before the state update) is equal to nonce.

  • r, s and v is a valid secp256k1 signature from owner of the message:

If any of these conditions are not met, the permit call must revert.

keccak256(abi.encodePacked(
hex"1901",
DOMAIN_SEPARATOR,
keccak256(abi.encode(
keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"),
owner,
spender,
value,
nonce,
deadline))
))

Impact

In TokenFacet.sol, there is no implementation of DOMAIN_SEPARATOR(). The contract will also be deployed on the L2 potentially, which poses a potential replay attack vulnerability.

Tools Used

Manual Review

Recommendations

Properly implement DOMAIN_SEPARATOR()

https://eips.ethereum.org/EIPS/eip-2612

Updates

Lead Judging Commences

inallhonesty Lead Judge over 1 year ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity

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