AirDropper
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Submission Details
Severity: high
Valid

Wrong USDC Token Address in Deploy Script Causes All Claims to Permanently Fail

sergios

Description

  • The deploy script creates the MerkleAirdrop contract by passing s_zkSyncUSDC as the airdrop token address, then separately transfers USDC into the new contract
    to fund it for distribution.

  • Two different addresses are used: s_zkSyncUSDC (0x1D17CbCf0D6d143135be902365d2e5E2a16538d4) is stored as i_airdropToken in the constructor, but the funding
    transfer() call uses 0x1d17CBcF0D6D143135ae902365D2E5e2A16538D4 — a different contract at byte 9 of the address. The deployed MerkleAirdrop holds zero
    balance of i_airdropToken, so every claim() call reverts on safeTransfer.

// script/Deploy.s.sol

@> address public s_zkSyncUSDC = 0x1D17CbCf0D6d143135be902365d2e5E2a16538d4;
// ^^
// 'b' here

 function run() public {
     vm.startBroadcast();
     MerkleAirdrop airdrop = deployMerkleDropper(s_merkleRoot, IERC20(s_zkSyncUSDC));
     // i_airdropToken = 0x1D17CbCf0D6d143135be902365d2e5E2a16538d4

@> IERC20(0x1d17CBcF0D6D143135aE902365D2E5e2A16538D4).transfer(address(airdrop), s_amountToAirdrop);
// ^^
// 'a' here — DIFFERENT ADDRESS
// Contract is funded with Token B, but i_airdropToken is Token A
vm.stopBroadcast();
}

Risk

Likelihood:

  • Every deployment using this script results in a broken contract — the address mismatch is hardcoded and triggers on every run() execution with no conditional
    path that avoids it.

  • Because i_airdropToken is immutable, there is no on-chain recovery mechanism; the contract must be redeployed and the incorrectly-funded tokens manually
    recovered from the wrong address.

Impact:

  • All four eligible addresses are permanently locked out of their airdrop — every claim() call reverts with insufficient balance because the contract holds none
    of the token it is configured to distribute.

  • The 100e6 USDC sent via the funding transfer() is deposited into the contract but belongs to a different token contract than i_airdropToken, making it
    unrecoverable through the normal claim() or claimFees() paths.

Proof of Concept

function test_H01_DeployAddressMismatch() public pure {
address configuredToken = 0x1D17CbCf0D6d143135bE902365d2e5E2a16538d4;
address fundingToken = 0x1d17CBcF0D6D143135aE902365D2E5e2A16538D4;

  // These are provably different addresses
  assert(configuredToken != fundingToken);

  // Consequence:
  // MerkleAirdrop is deployed with i_airdropToken = configuredToken
  // Contract is funded with fundingToken tokens
  // configuredToken.balanceOf(address(airdrop)) == 0
  // Every claim() → safeTransfer(configuredToken, account, amount) → reverts

}

Recommended Mitigation

// script/Deploy.s.sol

  • address public s_zkSyncUSDC = 0x1D17CbCf0D6d143135be902365d2e5E2a16538d4;

  • address public s_zkSyncUSDC = 0x1d17CBcF0D6D143135aE902365D2E5e2A16538D4;

Updates

Lead Judging Commences

ai-first-flight-judge Lead Judge about 4 hours ago
Submission Judgement Published
Validated
Assigned finding tags:

[H-01] Address of USDC token in `Deploy.s.sol` is wrong causing the claiming process to fail

## Description The `s_zkSyncUSDC` address in `Deploy.s.sol` is incorrectly set, leading to a failure in the claiming process. This error results in funds being stuck in the `MerkleAirdrop` contract due to the immutability of the token address. ## Impact All funds become permanently trapped in the `MerkleAirdrop` contract, rendering them inaccessible for claiming or transfer. **Proof of Concept:** To demonstrate the issue, a test contract can be added and executed using the following command: `forge test --zksync --rpc-url $RPC_ZKSYNC --mt testDeployOnZkSync` Use the RPC URL `https://mainnet.era.zksync.io` for testing. <details> <summary>Proof Of Code</summary> ```javascript // SPDX-License-Identifier: MIT pragma solidity 0.8.24; import { MerkleAirdrop, IERC20 } from "../src/MerkleAirdrop.sol"; import { Test, console2 } from "forge-std/Test.sol"; contract MerkleAirdropTest is Test { MerkleAirdrop public s_airdrop; uint256 s_amountToCollect = (25 * 1e6); // 25.000000 address s_collectorOne = 0x20F41376c713072937eb02Be70ee1eD0D639966C; bytes32 s_proofOne = 0x32cee63464b09930b5c3f59f955c86694a4c640a03aa57e6f743d8a3ca5c8838; bytes32 s_proofTwo = 0x8ff683185668cbe035a18fccec4080d7a0331bb1bbc532324f40501de5e8ea5c; bytes32[] s_proof = [s_proofOne, s_proofTwo]; address public deployer; // From Deploy.t.sol bytes32 public s_merkleRoot = 0x3b2e22da63ae414086bec9c9da6b685f790c6fab200c7918f2879f08793d77bd; address public s_zkSyncUSDC = 0x1d17CBcF0D6D143135aE902365D2E5e2A16538D4; uint256 public s_amountToAirdrop = 4 * (25 * 1e6); function setUp() public { deployer = makeAddr("deployer"); deal(0x1D17CbCf0D6d143135be902365d2e5E2a16538d4, deployer, 100 * 1e6); vm.deal(s_collectorOne, 100 ether); } function testDeployOnZkSync() public { if (block.chainid != 324) { return; } vm.startPrank(deployer); // From here there is the code from run() s_airdrop = deployMerkleDropper(s_merkleRoot, IERC20(s_zkSyncUSDC)); // Send USDC -> Merkle Air Dropper IERC20(0x1d17CBcF0D6D143135aE902365D2E5e2A16538D4).transfer(address(s_airdrop), s_amountToAirdrop); // end code from run vm.stopPrank(); vm.startPrank(s_collectorOne); s_airdrop.claim{ value: s_airdrop.getFee() }(s_collectorOne, s_amountToCollect, s_proof); vm.stopPrank(); } function deployMerkleDropper(bytes32 merkleRoot, IERC20 zkSyncUSDC) public returns (MerkleAirdrop) { return (new MerkleAirdrop(merkleRoot, zkSyncUSDC)); } } ``` </details> ## Recommendations To resolve the issue, update the s_zkSyncUSDC address in Deploy.s.sol to the correct value: ```diff - address public s_zkSyncUSDC = 0x1D17CbCf0D6d143135be902365d2e5E2a16538d4; + address public s_zkSyncUSDC = 0x1d17CBcF0D6D143135aE902365D2E5e2A16538D4; ```

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