QA Report

[code423n4]

1. USE OF FLOATING PRAGMA

Recommend using fixed solidity version

Instances

// Links to githubfile

https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IAxelarAuth.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IAxelarAuthWeighted.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IAxelarDepositService.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IDepositBase.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IAxelarGasService.sol#L3

// actual codes 

contracts/interfaces/IAxelarAuth.sol:3:pragma solidity ^0.8.9;
contracts/interfaces/IAxelarAuthWeighted.sol:3:pragma solidity ^0.8.9;
contracts/interfaces/IAxelarDepositService.sol:3:pragma solidity ^0.8.9;
contracts/interfaces/IDepositBase.sol:3:pragma solidity ^0.8.9;
contracts/interfaces/IAxelarGasService.sol:3:pragma solidity ^0.8.9;

2. safeApprove() is deprecated

This is probably an oversight since SafeERC20 was imported and safeTransfer() was used for ERC20 token transfers. Nevertheless, note that approve() will fail for certain token implementations that do not return a boolean value (). Hence it is recommend to use safeApprove().

Instances

//Links to github file

https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/ReceiverImplementation.sol#L38 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/ReceiverImplementation.sol#L64 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/AxelarDepositService.sol#L30

actual codes 
contracts/deposit-service/ReceiverImplementation.sol:38:        IERC20(tokenAddress).approve(gateway, amount);
contracts/deposit-service/ReceiverImplementation.sol:64:        IERC20(wrappedTokenAddress).approve(gateway, amount);
contracts/deposit-service/AxelarDepositService.sol:30:        IERC20(wrappedTokenAddress).approve(gateway, amount);

3. USE SAFETRANSFER()/SAFETRANSFERFROM() INSTEAD OF TRANSFER()/TRANSFERFROM()

It is a good idea to add a require() statement that checks the return value of ERC20 token transfers or to use something like OpenZeppelin’s safeTransfer()/safeTransferFrom() unless one is sure the given token reverts in case of a failure. Failure to do so will cause silent failures of transfers and affect token accounting in contract.

However, using require() to check transfer return values could lead to issues with non-compliant ERC20 tokens which do not return a boolean value. Therefore, it’s highly advised to use OpenZeppelin’s safeTransfer()/safeTransferFrom().

Instances

// Links to github file https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L107 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L501 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L523

//actual codes
xc20/contracts/XC20Wrapper.sol:107:            abi.encodeWithSelector(IERC20.transferFrom.selector, from, address(this), amount)
contracts/AxelarGateway.sol:501:                abi.encodeWithSelector(IERC20.transferFrom.selector, sender, address(this), amount)
contracts/AxelarGateway.sol:523:                IERC20.transferFrom.selector,

4. UNUSED/EMPTY RECEIVE()/FALLBACK() FUNCTION

If the intention is for the Ether to be used, the function should call another function, otherwise it should revert (e.g. require(msg.sender == address(weth)))

There are 2 instances of this issue:

Instances

//Links to githubfile https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/AxelarDepositServiceProxy.sol#L13 https://github.com/code-423n4/2022-07-axelar/blob/main/contractsdeposit-service/DepositReceiver.sol#L29

//actual codes
contracts/deposit-service/AxelarDepositServiceProxy.sol:13:    receive() external payable override {}
contracts/deposit-service/DepositReceiver.sol:29:    receive() external payable {}

5. Use of recent version of Solidity

Instances

// Links to githubfile

https://github.com/code-423n4/2022-07-axelar/blob/main/xc20/contracts/XC20Wrapper.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IAxelarAuth.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IAxelarAuthWeighted.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IAxelarDepositService.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IDepositBase.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/interfaces/IAxelarGasService..sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/ReceiverImplementation.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/AxelarDepositServiceProxy.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/DepositReceiver.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/DepositBase.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/deposit-service/AxelarDepositService.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/auth/AxelarAuthWeighted.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/AxelarGateway.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/gas-service/AxelarGasServiceProxy.sol#L3 https://github.com/code-423n4/2022-07-axelar/blob/main/contracts/gas-service/AxelarGasService.sol#L3

// actual codes 

xc20/contracts/XC20Wrapper.sol:3:pragma solidity 0.8.9;
contracts/interfaces/IAxelarAuth.sol:3:pragma solidity ^0.8.9;
contracts/interfaces/IAxelarAuthWeighted.sol:3:pragma solidity ^0.8.9;
contracts/interfaces/IAxelarDepositService.sol:3:pragma solidity ^0.8.9;
contracts/interfaces/IDepositBase.sol:3:pragma solidity ^0.8.9;
contracts/interfaces/IAxelarGasService.sol:3:pragma solidity ^0.8.9;
contracts/deposit-service/ReceiverImplementation.sol:3:pragma solidity 0.8.9;
contracts/deposit-service/AxelarDepositServiceProxy.sol:3:pragma solidity 0.8.9;
contracts/deposit-service/DepositReceiver.sol:3:pragma solidity 0.8.9;
contracts/deposit-service/DepositBase.sol:3:pragma solidity 0.8.9;
contracts/deposit-service/AxelarDepositService.sol:3:pragma solidity 0.8.9;
contracts/auth/AxelarAuthWeighted.sol:3:pragma solidity 0.8.9;
contracts/AxelarGateway.sol:3:pragma solidity 0.8.9;
contracts/gas-service/AxelarGasServiceProxy.sol:3:pragma solidity 0.8.9;
contracts/gas-service/AxelarGasService.sol:3:pragma solidity 0.8.9;

[GalloDaSballo]

1. USE OF FLOATING PRAGMA

NC

2. safeApprove() is deprecated

Disputed as approve is used as intended in this codebase

3. USE SAFETRANSFER()/SAFETRANSFERFROM() INSTEAD OF TRANSFER()/TRANSFERFROM()

L

 4. UNUSED/EMPTY RECEIVE()/FALLBACK() FUNCTION

L

5. Use of recent version of Solidity

NC

2L 2NC