Read the findings of the 2022 Web3 Security Report

The contracts `CarvAchievements` and `CarvEvents` are upgradeable since they are sub-contracts of `UUPSUpgradeable`. 

The role `proxy`, can call the below function `upgradeTo` in OpenZeppelin Contracts version v4.5.0, to update the implementation by the `proxy`.
```solidity
    function upgradeTo(address newImplementation) external virtual onlyProxy {
        _authorizeUpgrade(newImplementation);
        _upgradeToAndCallUUPS(newImplementation, new bytes(0), false);
    }
```    

Any compromise to the `proxy` account may allow a hacker to take advantage of this authority.

Centralization Risk - Upgradeable Contracts

The implementations of imported source files started with `@openzeppelin` need to be checked when deploying, and we understand the protocol depends on the 3rd party libraries, however, it is out of this audit scope and should be validated before deploying the protocol in the production environment. 

Unknown implementations

When transferring standard ERC20 deflationary tokens, the input amount may not be equal to the received amount due to the charged transaction fee. For example, if a user fills an offer with 100 deflationary tokens (with a 10% transaction fee) in `CarvINOERC20`, only 90 tokens actually arrived in the contract. However, the price of the NFT is 100 tokens from the contract, which causes the contract to lose 10 tokens in such a transaction. 

Incompatibility With Deflationary Tokens

Although not explicitly declared, the contract `CarvAchievements` and `CarvEvents` implement the EIP-2771. The variable `_trustedForwarders` serves as a 3rd party forwarder to help it identify the address of the Transaction Signer. The contract `CarvAchievements` and `CarvEvents` override the `_msgSender()` function to decode the `msg.sender` from `msg.data` if it is called from the forwarder. The scope of the audit treats these 3rd party forwarders as black boxes and assumes their functional correctness. However, in the real world, 3rd parties can be compromised and this may lead to lost or stolen assets. In addition, upgrades of 3rd parties can possibly create severe impacts.

Reference: [EIP-2771](https://eips.ethereum.org/EIPS/eip-2771)

Unknow Trusted Forwarder Implementation

```solidity=165
        if (isTrustedForwarder(msg.sender)) {
            assembly {
                sender := shr(96, calldataload(sub(calldatasize(), 20)))
            }
        } else {
            return super._msgSender();
        }
```
If the `msg.sender` is a trusted forwarder, we trust that the last bytes of `msg.data` are the verified sender address and will extract sender address from the end of `msg.data` by `shr(96, calldataload(sub(calldatasize(), 20)))`. 

If an EOA address is incorrectly set as a trusted forwarder, its call data may be empty so that the calculation `sub(calldatasize(), 20)` will fail.


Length Of `msg.data` Not Check

There should always be events emitted in the sensitive functions that are controlled by centralization roles.

Missing Emit Events

The contract has unlocked compiler version. An unlocked compiler version in the source code of the contract permits the user to compile it at or above a particular version. This, in turn, leads to differences in the generated bytecode between compilations due to differing compiler version numbers. This can lead to an ambiguity when debugging as compiler specific bugs may occur in the codebase that would be hard to identify over a span of multiple compiler versions rather than a specific one.

Unlocked Compiler Version

Public functions that are never called by the contract could be declared as `external`. When the inputs are arrays external functions are more efficient than `public` functions.

Proper Usage of `public` and `external` type

Due to a vulnerability in OpenZeppelin Contracts v4.1.0 through v4.3.1, all projects using the UUPS proxy pattern should initialize their implementation contracts.

Reference:
- [security-advisory-initialize-uups-implementation-contracts](https://forum.openzeppelin.com/t/security-advisory-initialize-uups-implementation-contracts/15301)
- [uupsupgradeable-vulnerability-post-mortem](https://forum.openzeppelin.com/t/uupsupgradeable-vulnerability-post-mortem/15680)


When the version of OpenZeppelin Contracts is v4.1.0 through v4.3.1, `CarvAchievements` will be an upgradeable contract that does not protect its initiliaze functions: `CarvAchievements.initialize()`. Anyone can delete the contract with: `UUPSUpgradeable.upgradeTo(address)` 
 and `UUPSUpgradeable.upgradeToAndCall(address,bytes)`.


When the version of OpenZeppelin Contracts is v4.1.0 through v4.3.1, `CarvEvents` will be an upgradeable contract that does not protect its initiliaze functions: `CarvEvents.initialize()`. Anyone can delete the contract with: `UUPSUpgradeable.upgradeTo(address)` and `UUPSUpgradeable.upgradeToAndCall(address,bytes)`.


Unprotected Upgradeable Contract

The proxy contract `CarvAchievementsProxy` and `CarvEventsProxy` do not have a predefined execution contract. The audit scope treats the third-party entity as a black box and assumes that it functions correctly. However, in the real world, third parties can be compromised, which can lead to the loss or theft of assets. In addition, third-party upgrades can have serious implications, such as increased third-party fees, migration to new implementation contracts, etc.

Unknown Implementation of Proxy

In the contract `CarvEvents` the role `_owner` has authority over the functions shown in the diagram below.
Any compromise to the `_owner` account may allow the hacker to take advantage of this authority.
![](https://accelerator-tasks-prod.s3.amazonaws.com/e0c03c356d094ac5b2d1fcca602bd1a4/diagrams/centralization_CarvEvents__owner.svg)

In commit a7f1ea88a4ef4ade4c7b7088ff5245419e9feec4, the role `_owner` authority over the following functions:
- `pause`
- `unpause`

In the contract `CarvAchievements` the role `_owner` has authority over the functions shown in the diagram below.
Any compromise to the `_owner` account may allow the hacker to take advantage of this authority.
![](https://accelerator-tasks-prod.s3.amazonaws.com/e0c03c356d094ac5b2d1fcca602bd1a4/diagrams/centralization_CarvAchievements__owner.svg)

In commit a7f1ea88a4ef4ade4c7b7088ff5245419e9feec4, the role `_owner` authority over the following functions:
- `pause`
- `unpause`

In the contract `CarvINO`, the role `DEFAULT_ADMIN_ROLE` has authority over the following functions:
- `setNFTCollection`
- `setUnitPrice`
- `setMinPurchase`
- `setMaxOfferCount`
- `pause`
- `unpause`
- `setRequireWhitelist`
- `setWhitelist`
- `setWhitelistBatch`
- `getOffer`

Any compromise to the `DEFAULT_ADMIN_ROLE` account may allow a hacker to take advantage of this authority.

In the contract `CarvINO`, the role `MAKE_OFFER_ROLE` has authority over the following functions:
- `addOffer`
- `addOfferBatch`

Any compromise to the `CLAIM_FUND_ROLE` account may allow a hacker to take advantage of this authority.

In the contract `CarvINO`, the role `CLAIM_FUND_ROLE` has authority over the following functions:
- `claimFund`

Any compromise to the `CLAIM_FUND_ROLE` account may allow a hacker to take advantage of this authority.

In the contract `CarvINO`, the role `CLAIM_STOCK_ROLE` has authority over the following functions:
- `claimRemainingStock`

Any compromise to the `CLAIM_STOCK_ROLE` account may allow a hacker to take advantage of this authority.

In the contract `CarvINOERC20`, the role `DEFAULT_ADMIN_ROLE` has authority over the following functions:
- `setNFTCollection`
- `setPaymentToken`
- `setUnitPrice`
- `setMinPurchase`
- `setMaxOfferCount`
- `pause`
- `unpause`
- `setRequireWhitelist`
- `setWhitelist`
- `setWhitelistBatch`
- `getOffer`

Any compromise to the `DEFAULT_ADMIN_ROLE` account may allow a hacker to take advantage of this authority.

In the contract `CarvINOERC20`, the role `MAKE_OFFER_ROLE` has authority over the following functions:
- `addOffer`
- `addOfferBatch`

Any compromise to the `CLAIM_FUND_ROLE` account may allow a hacker to take advantage of this authority.

In the contract `CarvINOERC20`, the role `CLAIM_FUND_ROLE` has authority over the following functions:
- `claimFund`

Any compromise to the `CLAIM_FUND_ROLE` account may allow a hacker to take advantage of this authority.

In the contract `CarvINOERC20`, the role `CLAIM_STOCK_ROLE` has authority over the following functions:
- `claimRemainingStock`

Any compromise to the `CLAIM_STOCK_ROLE` account may allow a hacker to take advantage of this authority.


Centralization Related Risks

Carv

CarvINOERC20.sol

CarvAchievementsProxy.sol

Carv

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Code Audit History

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