Liquidity Management
Gamma
DeFiFoundry
50,000 USDC
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Submission Details
Severity: low
Invalid

Unchecked ETH Transfer

glitchunter

Summary

The withdrawEth() function in GmxProxy.sol transfers the entire contract balance to msg.sender without verifying that the recipient address is valid. If msg.sender is an unintended address or an externally owned account (EOA) that cannot receive ETH, the transfer could fail or be exploited by a compromised admin.

Vulnerability Details

GmxProxy.sol::withdrawEth
There is no check to ensure that msg.sender is a valid recipient.
If msg.sender is an address that cannot receive ETH (e.g., a contract without a payable fallback function), the transfer will fail.
Lack of Failure Handling: transfer() only provides 2300 gas and reverts on failure, meaning if msg.sender is a contract with a non-payable fallback function, the withdrawal will fail.

POC

contract NonPayableReceiver {
fallback() external { revert("Cannot receive ETH"); }
}

If the contract owner is set to NonPayableReceiver, withdrawEth() will always fail.

  • If an attacker gains ownership of GmxProxy, they can call withdrawEth() to drain all ETH from the contract.

Impact

  • Funds Could Be Lost or Stuck: If msg.sender is unable to receive ETH, the function call will revert, preventing further operations.

  • Security Risk if Ownership is Compromised: If an attacker gains control of the owner role, they can drain all ETH from the contract.

Tools Used

Manual Review

Recommendations

Validate msg.sender Before Transferring ETH

Modify the function to ensure msg.sender is a valid recipient and use call instead of transfer to avoid gas limit issues:

function withdrawEth() external onlyOwner returns (uint256) {
uint256 balance = address(this).balance;
require(msg.sender != address(0), "Invalid recipient");
​
(bool success, ) = payable(msg.sender).call{value: balance}("");
require(success, "ETH transfer failed");
​
return balance;
}

  • Implement Access Control Mechanisms to prevent unauthorized ownership transfers.

Updates

Lead Judging Commences

n0kto Lead Judge 9 months ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity
Assigned finding tags:

Admin is trusted / Malicious keepers

Please read the CodeHawks documentation to know which submissions are valid. If you disagree, provide a coded PoC and explain the real likelihood and the detailed impact on the mainnet without any supposition (if, it could, etc) to prove your point. Keepers are added by the admin, there is no "malicious keeper" and if there is a problem in those keepers, that's out of scope. ReadMe and known issues states: " * System relies heavily on keeper for executing trades * Single keeper point of failure if not properly distributed * Malicious keeper could potentially front-run or delay transactions * Assume that Keeper will always have enough gas to execute transactions. There is a pay execution fee function, but the assumption should be that there's more than enough gas to cover transaction failures, retries, etc * There are two spot swap functionalies: (1) using GMX swap and (2) using Paraswap. We can assume that any swap failure will be retried until success. " " * Heavy dependency on GMX protocol functioning correctly * Owner can update GMX-related addresses * Changes in GMX protocol could impact system operations * We can assume that the GMX keeper won't misbehave, delay, or go offline. " "Issues related to GMX Keepers being DOS'd or losing functionality would be considered invalid."

n0kto Lead Judge 9 months ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity
Assigned finding tags:

Admin is trusted / Malicious keepers

Please read the CodeHawks documentation to know which submissions are valid. If you disagree, provide a coded PoC and explain the real likelihood and the detailed impact on the mainnet without any supposition (if, it could, etc) to prove your point. Keepers are added by the admin, there is no "malicious keeper" and if there is a problem in those keepers, that's out of scope. ReadMe and known issues states: " * System relies heavily on keeper for executing trades * Single keeper point of failure if not properly distributed * Malicious keeper could potentially front-run or delay transactions * Assume that Keeper will always have enough gas to execute transactions. There is a pay execution fee function, but the assumption should be that there's more than enough gas to cover transaction failures, retries, etc * There are two spot swap functionalies: (1) using GMX swap and (2) using Paraswap. We can assume that any swap failure will be retried until success. " " * Heavy dependency on GMX protocol functioning correctly * Owner can update GMX-related addresses * Changes in GMX protocol could impact system operations * We can assume that the GMX keeper won't misbehave, delay, or go offline. " "Issues related to GMX Keepers being DOS'd or losing functionality would be considered invalid."

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