Security Audit
July 10th, 2024
Version 1.0.0
Presented by 0xMacro
This document includes the results of the security audit for Superstate's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team on July 3rd to July 5th, 2024.
The purpose of this audit is to review the source code of certain Superstate Solidity contracts, and provide feedback on the design, architecture, and quality of the source code with an emphasis on validating the correctness and security of the software in its entirety.
Disclaimer: While Macro’s review is comprehensive and has surfaced some changes that should be made to the source code, this audit should not solely be relied upon for security, as no single audit is guaranteed to catch all possible bugs.
The following is an aggregation of issues found by the Macro Audit team:
Severity | Count | Acknowledged | Won't Do | Addressed |
---|---|---|---|---|
Medium | 1 | - | - | 1 |
Code Quality | 8 | - | 4 | 4 |
Superstate was quick to respond to these issues.
Our understanding of the specification was based on the following sources:
The following source code was reviewed during the audit:
6efadf608c4941a6ce63a770adfd68cf0160d673
8bf5b29b7eb670778aeedd53342bbce4551b1385
Specifically, we audited the following contracts within this repository:
Contract | SHA256 |
---|---|
./src/AllowList.sol |
|
./src/SuperstateToken.sol |
|
./src/USCC.sol |
|
./src/USTB.sol |
|
Additionally, the following deployment script was reviewed:
Contract | SHA256 |
---|---|
./script/DeployUsccScript.s.sol |
|
Note: This document contains an audit solely of the Solidity contracts listed above. Specifically, the audit pertains only to the contracts themselves, and does not pertain to any other programs or scripts, including deployment scripts.
Click on an issue to jump to it, or scroll down to see them all.
SuperstateToken
is not EIP-2612 compliant
_releaseEncumbrance()
execution for transferFrom
calls with allowance only
Permission
states
USCC
state lacks a specific setter function
We quantify issues in three parts:
This third part – the severity level – is a summary of how much consideration the client should give to fixing the issue. We assign severity according to the table of guidelines below:
Severity | Description |
---|---|
(C-x) Critical |
We recommend the client must fix the issue, no matter what, because not fixing would mean significant funds/assets WILL be lost. |
(H-x) High |
We recommend the client must address the issue, no matter what, because not fixing would be very bad, or some funds/assets will be lost, or the code’s behavior is against the provided spec. |
(M-x) Medium |
We recommend the client to seriously consider fixing the issue, as the implications of not fixing the issue are severe enough to impact the project significantly, albiet not in an existential manner. |
(L-x) Low |
The risk is small, unlikely, or may not relevant to the project in a meaningful way. Whether or not the project wants to develop a fix is up to the goals and needs of the project. |
(Q-x) Code Quality |
The issue identified does not pose any obvious risk, but fixing could improve overall code quality, on-chain composability, developer ergonomics, or even certain aspects of protocol design. |
(I-x) Informational |
Warnings and things to keep in mind when operating the protocol. No immediate action required. |
(G-x) Gas Optimizations |
The presented optimization suggestion would save an amount of gas significant enough, in our opinion, to be worth the development cost of implementing it. |
SuperstateToken
is not EIP-2612 compliant
In SuperstateToken
, the permit()
feature currently has some divergences from the EIP-2612 standard specification:
The AUTHORIZATION_TYPEHASH
uses a different struct name.
/// @dev The EIP-712 typehash for authorization via permit
bytes32 internal constant AUTHORIZATION_TYPEHASH =
keccak256("Authorization(address owner,address spender,uint256 amount,uint256 nonce,uint256 expiry)");
Reference: SuperstateToken.sol#21-22
The permit
function parameters amount
and expiry
do not have the same parameter names.
function permit(address owner, address spender, uint256 amount, uint256 expiry, uint8 v, bytes32 r, bytes32 s)
Reference: SuperstateToken.sol#306
The expiry
check will revert if it’s equal to block.timestamp
.
if (block.timestamp >= expiry) revert SignatureExpired();
Reference: SuperstateToken.sol#L309
Different from what EIP-2612 states:
The current blocktime is less than or equal to
deadline
.
Reference: EIP-2612#Specification
This could cause external third-party integrators to fail to produce valid signatures to interact with SuperstateToken
reverting on permit()
calls and will need custom signature generation integration for this specific contract.
Remediations to Consider:
Changing the function’s parameter amount
and expiry
to value
and deadline
correspondingly.
Changing the AUTHORIZATION_TYPEHASH
to
keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
Updating the expiry
check to allow block.timestamp == expiry
.
_releaseEncumbrance()
execution for transferFrom
calls with allowance only
In SuperstateToken.sol
, function transferFrom()
checks the value of encumbered tokens that the intended src
address has set to the corresponding msg.sender
. If the amount
to be transferred is higher than the encumbered balance the logic checks if the proper allowance is set to execute a standard ERC20 transferFrom
.
function transferFrom(address src, address dst, uint256 amount) public override returns (bool) {
uint256 encumberedToTaker = encumbrances[src][msg.sender];
// check src permissions if amount encumbered is less than amount being transferred
if (encumberedToTaker < amount && !hasSufficientPermissions(src)) {
revert InsufficientPermissions();
}
if (amount > encumberedToTaker) {
uint256 excessAmount;
unchecked {
excessAmount = amount - encumberedToTaker;
}
// Ensure that `src` has enough available balance (funds not encumbered to others)
// to cover the excess amount
if (availableBalanceOf(src) < excessAmount) revert InsufficientAvailableBalance();
// Exceeds Encumbrance, so spend all of it
**_releaseEncumbrance(src, msg.sender, encumberedToTaker);**
_spendAllowance(src, msg.sender, excessAmount);
} else {
_releaseEncumbrance(src, msg.sender, amount);
}
...
return true;
}
Reference: SuperstateToken.sol#L224-259
However, this will execute _releaseEncumbrance()
and emit Release
even if this taker has no encumbered tokens. For example, all transferFrom()
calls using allowances will render this behavior. Consider checking if encumberedToTaker
is not equal to zero and calling _releaseEncumbrance()
if so.
Permission
states
In the AllowList
contract, the Permission
struct member names do not reflect the specific permission purpose of each permission state. Furthermore, the isAllowed
does not specify that it uniquely represents the authorized bool for USTB
contract. Similarly, the state1
does not represent the USCC
permission. Consider renaming these struct members to a more expressive name representing the proper authorization granted by them.
USCC
state lacks a specific setter function
TheAllowList
currently contains the setIsAllowed()
function to set the isAllowed
bool for a specific entityId
. However, there is no function to set the particular state1
for the USCC contract. Although this state can be set through setNthPermission()
, consider implementing a function to set this state to have a consistent interface.
As of the solidity 0.8.22 version, the compiler includes unchecked
counter increments for for
loops by default. Consider removing unnecessary gas optimizations for incrementing the counter in the for
statement in functions setEntityIdForMultipleAddresses()
and setEntityPermissionAndAddresses()
in Allowlist
.
Currently, all contracts set the required version for solidity pragma to a minimum value but do not specifically lock it to a fixed compiler version:
USTB
and USCC
use pragma solidity ^0.8.26
.Allowlist
and SuperstateToken
use pragma solidity ^0.8.20
.Consider using a single and fixed pragma version as a best practice.
Consider updating the OZ library to the latest stable release, 5.0.2, as it currently uses the 4.9.3 version.
In DeployUsccScript.s.sol
, the variable permsImplementation
is currently not being used. Consider removing it.
SuperstateToken
, USCC
, and USTB
are upgradeable contracts. However, the current implementation does not implement any strategy for preventing storage conflicts during future contract upgrades.
Consider implementing storage gaps or unstructured storage pattern to facilitate contract maintenance in the future.
Macro makes no warranties, either express, implied, statutory, or otherwise, with respect to the services or deliverables provided in this report, and Macro specifically disclaims all implied warranties of merchantability, fitness for a particular purpose, noninfringement and those arising from a course of dealing, usage or trade with respect thereto, and all such warranties are hereby excluded to the fullest extent permitted by law.
Macro will not be liable for any lost profits, business, contracts, revenue, goodwill, production, anticipated savings, loss of data, or costs of procurement of substitute goods or services or for any claim or demand by any other party. In no event will Macro be liable for consequential, incidental, special, indirect, or exemplary damages arising out of this agreement or any work statement, however caused and (to the fullest extent permitted by law) under any theory of liability (including negligence), even if Macro has been advised of the possibility of such damages.
The scope of this report and review is limited to a review of only the code presented by the Superstate team and only the source code Macro notes as being within the scope of Macro’s review within this report. This report does not include an audit of the deployment scripts used to deploy the Solidity contracts in the repository corresponding to this audit. Specifically, for the avoidance of doubt, this report does not constitute investment advice, is not intended to be relied upon as investment advice, is not an endorsement of this project or team, and it is not a guarantee as to the absolute security of the project. In this report you may through hypertext or other computer links, gain access to websites operated by persons other than Macro. Such hyperlinks are provided for your reference and convenience only, and are the exclusive responsibility of such websites’ owners. You agree that Macro is not responsible for the content or operation of such websites, and that Macro shall have no liability to your or any other person or entity for the use of third party websites. Macro assumes no responsibility for the use of third party software and shall have no liability whatsoever to any person or entity for the accuracy or completeness of any outcome generated by such software.