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Submission Details
Severity: low
Invalid

Unchecked ERC20 Transfer Return Values Leading to Silent Failures

Summary

The contract fails to check return values from ERC20 token transfers, which can lead to silent failures and accounting inconsistencies.

Vulnerability Details

ERC20 token transfers can fail silently if return values are not checked, leading to a mismatch between actual and recorded token balances.

The contract performs token transfers without checking their success:

function withdraw(uint256 amount) external {
token.transfer(msg.sender, amount); // Return value not checked
// State updates happen regardless of transfer success
balances[msg.sender] -= amount;
}

Some ERC20 tokens (like USDT) don't revert on failure and instead return false, which needs to be explicitly checked.

Impact

  • Silent transfer failures leading to accounting errors

  • Potential loss of user funds

  • Inconsistent contract state

  • Exploitation opportunities in complex transactions

PoC:

contract TokenTransferExploit {
function exploit(PerpVault vault, uint256 amount) external {
// Attempt withdrawal without sufficient balance
vault.withdraw(amount);
// Contract state updates even if transfer failed
}
}

Tools Used

  • Manual review

  • Mythril

  • OpenZeppelin Test Helpers

Recommendations

Use OpenZeppelin's SafeERC20 library:

using SafeERC20 for IERC20;
function withdraw(uint256 amount) external {
token.safeTransfer(msg.sender, amount);
balances[msg.sender] -= amount;
}
Updates

Lead Judging Commences

n0kto Lead Judge 9 months ago
Submission Judgement Published
Invalidated
Reason: Out of scope
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."

Suppositions

There is no real proof, concrete root cause, specific impact, or enough details in those submissions. Examples include: "It could happen" without specifying when, "If this impossible case happens," "Unexpected behavior," etc. Make a Proof of Concept (PoC) using external functions and realistic parameters. Do not test only the internal function where you think you found something.

n0kto Lead Judge 9 months ago
Submission Judgement Published
Invalidated
Reason: Out of scope
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."

Suppositions

There is no real proof, concrete root cause, specific impact, or enough details in those submissions. Examples include: "It could happen" without specifying when, "If this impossible case happens," "Unexpected behavior," etc. Make a Proof of Concept (PoC) using external functions and realistic parameters. Do not test only the internal function where you think you found something.

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