call() should be used instead of transfer() on an address payable

[code423n4]

Lines of code

https://github.com/code-423n4/2022-07-axelar/blob/94498f8ae1fb1df655dfb89f7f525f94d92f5de0/contracts/deposit-service/ReceiverImplementation.sol#L23
https://github.com/code-423n4/2022-07-axelar/blob/94498f8ae1fb1df655dfb89f7f525f94d92f5de0/contracts/deposit-service/ReceiverImplementation.sol#L51
https://github.com/code-423n4/2022-07-axelar/blob/94498f8ae1fb1df655dfb89f7f525f94d92f5de0/contracts/deposit-service/ReceiverImplementation.sol#L71
https://github.com/code-423n4/2022-07-axelar/blob/94498f8ae1fb1df655dfb89f7f525f94d92f5de0/contracts/deposit-service/ReceiverImplementation.sol#L86
https://github.com/code-423n4/2022-07-axelar/blob/94498f8ae1fb1df655dfb89f7f525f94d92f5de0/contracts/gas-service/AxelarGasService.sol#L128
https://github.com/code-423n4/2022-07-axelar/blob/94498f8ae1fb1df655dfb89f7f525f94d92f5de0/contracts/gas-service/AxelarGasService.sol#L144
https://github.com/code-423n4/2022-07-axelar/blob/94498f8ae1fb1df655dfb89f7f525f94d92f5de0/contracts/xc20/contracts/XC20Wrapper.sol#L63

Vulnerability details

This is a classic Code4rena issue:

• instead of call() , transfer() is used to withdraw the ether 2021-04-meebits-findings#2
• Swap.sol implements potentially dangerous transfer  2021-10-tally-findings#20
• OpenLevV1Lib's and LPool's doTransferOut functions call native payable.transfer, which can be unusable for smart contract calls 2022-01-openleverage-findings#75

Impact

The use of the deprecated transfer() function for an address will inevitably make the transaction fail when:

1. The claimer smart contract does not implement a payable function.
2. The claimer smart contract does implement a payable fallback which uses more than 2300 gas unit.
3. The claimer smart contract implements a payable fallback function that needs less than 2300 gas units but is called through proxy, raising the call's gas usage above 2300.

Additionally, using higher than 2300 gas might be mandatory for some multisig wallets.

Impacted lines:

deposit-service/ReceiverImplementation.sol:23:        if (address(this).balance > 0) refundAddress.transfer(address(this).balance);
deposit-service/ReceiverImplementation.sol:51:            if (address(this).balance > 0) refundAddress.transfer(address(this).balance);
deposit-service/ReceiverImplementation.sol:71:        if (address(this).balance > 0) refundAddress.transfer(address(this).balance);
deposit-service/ReceiverImplementation.sol:86:        recipient.transfer(amount);
gas-service/AxelarGasService.sol:128:                if (amount > 0) receiver.transfer(amount);
gas-service/AxelarGasService.sol:144:            receiver.transfer(amount);
xc20/contracts/XC20Wrapper.sol:63:        payable(msg.sender).transfer(address(this).balance);

Recommended Mitigation

Use call() instead of transfer(), but be sure to respect the CEI pattern and/or add re-entrancy guards, as several hacks already happened in the past due to this recommendation not being fully understood.

Relevant links:
https://twitter.com/hacxyk/status/1520715516490379264?s=21&t=fnhDkcC3KpE_kJE8eLiE2A
https://twitter.com/hacxyk/status/1520715536325218304?s=21&t=fnhDkcC3KpE_kJE8eLiE2A
https://twitter.com/hacxyk/status/1520370441705037824?s=21&t=fnhDkcC3KpE_kJE8eLiE2A
https://twitter.com/Hacxyk/status/1521949933380595712

[GalloDaSballo]

Similar to #230

[re1ro]

Duplicate of #4