The Standard
The Standard
DeFiHardhat
20,000 USDC
View results
Previous Next
Submission Details
Severity: low
Invalid

Lack of Token Approval Before Transfer

mylifechangefast

Summary

The safeTransferFrom function is commonly used to transfer tokens between addresses in a secure manner, especially when working with ERC-20 tokens. In Ethereum, for a contract to move tokens on behalf of an account, the account needs to approve the contract to spend a certain amount of tokens using the approve function but it doesn't seem to be as expected

Vulnerability Details

function distributeFees(uint256 _amount) external onlyManager {
uint256 tstTotal = getTstTotal();
if (tstTotal > 0) {
<------ @audit no approval function here!
IERC20(EUROs).safeTransferFrom(msg.sender, address(this), _amount);
for (uint256 i = 0; i < holders.length; i++) {
address _holder = holders[i];
positions[_holder].EUROs += _amount * positions[_holder].TST / tstTotal;
}
for (uint256 i = 0; i < pendingStakes.length; i++) {
pendingStakes[i].EUROs += _amount * pendingStakes[i].TST / tstTotal;
}
}
}
POC
// Assume ERC-20 interface with the necessary functions
interface IERC20 {
function safetransferFrom(address sender, address recipient, uint256 amount) external returns (bool);
function safeApprove(address spender, uint256 amount) external returns (bool);
// Other functions...
}
​
// Since EUROs here is an ERC-20 token
IERC20 public EUROs;
​
// Function that may cause issues without proper approval
function unsafeTransfer(uint256 amount, address to) external {
// This can potentially fail if msg.sender has not approved the contract
EUROs.safeTransferFrom(msg.sender, to, amount);
}

In this example, the unsafeTransfer function attempts to transfer amount of EUROs from msg.sender to another address using EUROs.tsaferansferFrom. However, if msg.sender has not previously approved this contract to spend EUROs on its behalf using safeApprove, the transaction will revert.

Impact

Without proper approval using the approve function, attempts to transfer tokens using transferFrom may fail, resulting in reverted transactions. Users expecting successful token transfers could face unexpected errors.

Tools Used

Manual Review

Recommendations

function distributeFees(uint256 _amount) external onlyManager {
uint256 tstTotal = getTstTotal();
if (tstTotal > 0) {
+ IERC20(EUROs).safeApprove(address(this), _amount);
IERC20(EUROs).safeTransferFrom(address(this), _amount);
for (uint256 i = 0; i < holders.length; i++) {
address _holder = holders[i];
positions[_holder].EUROs += _amount * positions[_holder].TST / tstTotal;
}
for (uint256 i = 0; i < pendingStakes.length; i++) {
pendingStakes[i].EUROs += _amount * pendingStakes[i].TST / tstTotal;
}
}
}
Updates

Lead Judging Commences

hrishibhat Lead Judge almost 2 years ago
Submission Judgement Published
Invalidated
Reason: Known issue
Assigned finding tags:

informational/invalid

Support

FAQs

Can't find an answer? Chat with us on Discord, Twitter or Linkedin.

Give us feedback!