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Security Audit
October 2, 2023
Version 1.0.0
Presented by 0xMacro
This document includes the results of the security audit for Nori's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team from September 12, 2023 to September 18, 2023.
The purpose of this audit is to review the source code of certain Nori 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 | 4 | - | - | 4 |
| Gas Optimization | 1 | - | - | 1 |
Nori 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:
1dac591651e554cecec4909ab1d565b9c0ae767c
Specifically, we audited the following contracts within this repository:
| Contract | SHA256 |
|---|---|
| ./contracts/ArrayLib.sol |
|
| ./contracts/Certificate.sol |
|
| ./contracts/Errors.sol |
|
| ./contracts/ICertificate.sol |
|
| ./contracts/IERC20WithPermit.sol |
|
| ./contracts/IMarket.sol |
|
| ./contracts/IRemoval.sol |
|
| ./contracts/IRestrictedNORI.sol |
|
| ./contracts/Market.sol |
|
| ./contracts/Removal.sol |
|
| ./contracts/RemovalIdLib.sol |
|
| ./contracts/RemovalsByYearLib.sol |
|
| ./contracts/RestrictedNORI.sol |
|
| ./contracts/RestrictedNORILib.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. |
_priceMultiple can be set lower than 100
In Market.sol the setter function setPurchasingTokenAndPriceMultiple() allows to set the price multiple to any arbitrary unbounded value.
However, if the value is set lower than 100, the calculations would lose precision and break the assumption used in price logic.
Remediations to Consider
Consider checking whether the provided value for the priceMultiple is equal to or higher than 100.
Removal.sol confusing naming for function and variable
In the _beforeTransfer() logic, to perform the proper input sanity checks and validations there is a function and a local variable with the same isValidTransfer name. Consider changing one of these to avoid any potential confusion with the separate checks each element is used for.
MARKET_ADMIN_ROLE access control role
The current documentation is missing the following allowed operations for the MARKET_ADMIN_ROLE:
setPurchasingTokenAndPriceMultiple().replace().swapWithoutFeeSpecialOrder().Consider updating the access control documentation for MARKET_ADMIN_ROLE to better communicate all potential gated operations it can perform.
feeDecimals should be a constant
In Market.sol, function _validateCertificateAmount() (lines 1412 to 1418) declares the feeDecimals variable and assigns it with a constant value that’s only being used as a read-only value. Consider making this variable a constant.
In Market.sol, there are two different implementations for the same loop logic conditions:
uint256 vintage = supplierRemovalQueue.earliestYear;
uint256 latestYear = supplierRemovalQueue.latestYear;
for (; vintage <= latestYear; ++vintage) {
for (
uint256 vintage = supplierRemovalQueue.earliestYear;
vintage <= latestYear;
++vintage
) {
slice() logic can be improved
The Market.sol contract's replace() and _fulfillorder() functions utilize the slice() function from the ArrayLib to create new arrays for ids and amounts, which contain the actual filled values for the supply allocation. This process essentially shortens the length of the initial array to match the number of listed supplies that were used by storing the same values that are in the original array in a new memory array.
One way to improve this implementation is by overriding the length of the memory array with the count of supplies used. This involves using the known value of the count and storing it in the memory slot where the array is declared. Doing so will reduce the complexity of each slice() call from O(n) to O(1), leading to significant reductions in both complexity and gas costs. It is important to note that since assembly blocks cannot directly access nested data type members, the array memory slot must be pre-calculated and used in the mstore.
A code implementation would look similar to this:
assembly {
/**
* Update length of `array` to `count`
* `array` is declared at 0x80 in this example
*
* This will override the length value stored in the array position
* note that this won't remove the elements stored in the original remaining indexes
*/
mstore(0x80, count)
}
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The scope of this report and review is limited to a review of only the code presented by the Nori 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.