The contract WellUpgradeable has heavily modified the upgrade mechanism of the UUPS upgrade pattern for compatibility with the ERC-1167 minimal proxy pattern in hopes of achieving more gas-efficient contract creation. This has introduced significant complexity and potential security risks.
In particular, the use of the implementation slot (_IMPLEMENTATION_SLOT) may be prone to attacks, where a malicious user can manipulate this value, leading to an incorrect contract being used as the target implementation.
Additionally, the _authorizeUpgrade method requires extensive and complex checks to ensure that updates are legitimately performed. This complexity could lead to accidental vulnerabilities.
Proof of Concept
The complicated upgrade mechanism is evident in these method implementations:
function _authorizeUpgrade(address newImplmentation) internal view override {...}
function upgradeTo(address newImplementation) public override {...}
function upgradeToAndCall(address newImplementation, bytes memory data) public payable override {...}
function proxiableUUID() external view override notDelegatedOrIsMinimalProxy returns (bytes32) {...}
Tools Used
Manual review
Recommended Mitigation Steps
It is generally recommended to follow well-established and audited patterns and libraries for implementing upgradable contracts, such as the OpenZeppelin library. This reduces the complexity and risk of introducing new security vulnerabilities, and increases code maintainability and understandability.
If the approach in the contract is intended, it is crucial to ensure each part of the added complexity is thoroughly reviewed and tested, with the code's assumptions and constraints being clearly documented.
Furthermore, custom upgrade logic should be designed to fail-close, i.e., refuse upgrades in any case that is not explicitly allowed, rather than attempting to enumerate and prevent all unsafe cases.
Lines of code
https://github.com/code-423n4/2024-07-basin/blob/main/src/WellUpgradeable.sol#L65-L120
Vulnerability details
Impact
The contract
WellUpgradeablehas heavily modified the upgrade mechanism of the UUPS upgrade pattern for compatibility with the ERC-1167 minimal proxy pattern in hopes of achieving more gas-efficient contract creation. This has introduced significant complexity and potential security risks.In particular, the use of the implementation slot (
_IMPLEMENTATION_SLOT) may be prone to attacks, where a malicious user can manipulate this value, leading to an incorrect contract being used as the target implementation.Additionally, the
_authorizeUpgrademethod requires extensive and complex checks to ensure that updates are legitimately performed. This complexity could lead to accidental vulnerabilities.Proof of Concept
The complicated upgrade mechanism is evident in these method implementations:
Tools Used
Manual review
Recommended Mitigation Steps
It is generally recommended to follow well-established and audited patterns and libraries for implementing upgradable contracts, such as the OpenZeppelin library. This reduces the complexity and risk of introducing new security vulnerabilities, and increases code maintainability and understandability.
If the approach in the contract is intended, it is crucial to ensure each part of the added complexity is thoroughly reviewed and tested, with the code's assumptions and constraints being clearly documented.
Furthermore, custom upgrade logic should be designed to fail-close, i.e., refuse upgrades in any case that is not explicitly allowed, rather than attempting to enumerate and prevent all unsafe cases.
Assessed type
Upgradable