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Security Audit
July 21, 2023
Version 1.0.0
Presented by 0xMacro
This document includes the results of the security audit for Kwenta's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team from July 17, 2023 to July 20, 2023.
The purpose of this audit is to review the source code of certain Kwenta 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 |
|---|---|---|---|---|
| Code Quality | 2 | - | - | 2 |
| Informational | 1 | 1 | - | - |
| Gas Optimization | 2 | - | - | 2 |
Kwenta 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:
5cc3ccc3817d41ad28e2b777450b308f460c9d4c
Specifically, we audited the following contracts within this repository:
| Contract | SHA256 |
|---|---|
| src/Account.sol |
|
| src/Events.sol |
|
| src/Settings.sol |
|
| src/utils/uniswap/BytesLib.sol |
|
| src/utils/uniswap/Constants.sol |
|
| src/utils/uniswap/SafeCast160.sol |
|
| src/utils/uniswap/V3Path.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.
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. |
In Account.sol when the owner swaps tokens using the UNISWAP_V3_SWAP command, in _uniswapV3Swap() the account contract approves the PERMIT2 address for the tokenIn and also calls approves the UNISWAP_UNIVERSAL_ROUTER address on PERMIT2 on the same tokenIn.
// approve Permit2 to spend _amountIn of this contract's tokenIn
IERC20(tokenIn).approve(address(PERMIT2), _amountIn);
// approve tokens to be swapped via Universal Router
PERMIT2.approve({
token: tokenIn,
spender: address(UNISWAP_UNIVERSAL_ROUTER),
amount: _amountIn.toUint160(),
/// @dev timstamp will never overflow (i.e. maximum value of uint48 is year 8 million 921 thousand 556)
expiration: uint48(block.timestamp)
});
Reference: Account.sol#L1045-L1055
However, if the desired tokens to swap are directly sent to the UNISWAP_UNIVERSAL_ROUTER address before calling _universalRouterExecute() and the payerIsUser value set as data for the UNISWAP_UNIVERSAL_ROUTER's execute() input is set to false, then these approvals can be removed.
Remediations to Consider
Remove the approvals and transfer the tokenIn to the UNISWAP_UNIVERSAL_ROUTER instead of the contract in the case where MarginAsset == tokenIn, otherwise transfer assetIn from the contract directly. Also set payerIsUser to be false. Doing so can reduce gas costs of executing swaps.
nonReentrant called excess times
In Account.sol’s dispatch() function has a nonReentrant modifier that prevents reentrancy. However, dispatch() is internal and only called by execute() for each command. This means that the locked value will be read and set twice per call to dispatch for each command execute, but it only needs to be set once in execute()
Remediations to Consider
Move the nonReentrant modifier from dispatch() to the execute() function to prevent unnecessary calls to the nonReentrant modifier.
In Events.sol, the function emitExecutorFeeSet() is never called. It implies that an account can set their own executor fee, but that is currently not the case.
Remediations to Consider
Remove emitExecutorFeeSet() and its associated ExecutorFeeSet event as they are not used.
payable casting
In Account.sol’s _payExecutorFee(), when the executor is not Gelato, the ETH fee is sent to the executor via a low level call.
fee = SETTINGS.executorFee();
(bool success,) = payable(msg.sender).call{value: fee}("");
if (!success) revert CannotPayExecutorFee(fee, msg.sender);
Reference: (Account.sol#L911-L913)[https://github.com/Kwenta/smart-margin/blob/5cc3ccc3817d41ad28e2b777450b308f460c9d4c/src/Account.sol#L911-L913]
However, low level calls to transfer ETH do not require the address to be set to payable.
Remediations to Consider
Remove the casting of msg.sender to payable.
executorFee
The executorFee used to pay for the execution of conditional orders, in the case where the executor is not gelato, is set by the owner of the Settings.sol contract, and cannot be adjusted by account owners. In times where gas prices cause conditional order execution to be more expensive than the currently set fee, then gelato will most likely be the only executor of the conditional order. Conversely, if the currently set fee is much lower than the gas cost to execute, it will most likely occur quickly but will may be executed for a larger fee than what Gelato would have charged if they executed the order.
Can be remedied via robust chain monitoring and quick calibration response
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The scope of this report and review is limited to a review of only the code presented by the Kwenta 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.