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

Insufficient Calldata Validation in ParaSwap Integration

certikfire

Summary

The ParaSwapUtils library implements insufficient validation of calldata when interacting with the ParaSwap Augustus Router. The current implementation only validates the receiver address at a fixed offset, which could potentially allow attackers to call unintended functions on the Router contract.

Vulnerability Details

In ParaSwapUtils.sol, the calldata validation is implemented as follows:

function _validateCallData(address to, bytes memory callData) internal view {
​
require(to == address(0xDEF171Fe48CF0115B1d80b88dc8eAB59176FEe57), "invalid paraswap callee");
​
address receiver;
​
assembly {
​
receiver := mload(add(callData, 196))
​
}
​
require(receiver == address(this), "invalid paraswap calldata");
​
}
​

The vulnerability exists because:

  • The function selector is not validated, allowing any function on the Router to be called

  • The receiver address is checked at a fixed offset (196), assuming all valid calls follow the same calldata layout

  • This assumption may not hold true for non-standard swap functions

An attacker could:

  • Craft calldata for an unintended function

  • Carefully construct parameters so that the value at offset 196 equals the contract address

  • Bypass the validation to call unexpected functions on the Router

Proof of Concept:

function demonstrateVulnerability() public {
​
​
*// Craft malicious calldata*
​
bytes memory maliciousCalldata = abi.encodeWithSelector(
​
bytes4(keccak256("someUnintendedFunction()")),
​
*// Parameters crafted to pass validation*
​
...
​
);
​
​
*// Call will pass validation but execute unintended function*
​
paraSwapUtils.swap(AUGUSTUS\_ROUTER, maliciousCalldata);
​
}

Impact

The vulnerability could potentially allow:

  • Calling unintended functions on the ParaSwap Router

  • Bypassing expected swap validation

  • Possible manipulation of token approvals and transfers

    The actual impact depends on the available public functions in the Router contract

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."

invalid_ParaswapUtils_swap_malicious_callData

This function call only reached via a function called by the keeper. So no malicious callData will be provided.

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