Exploit Reproduction And Analysis

Exploit Reproduction & Analysis

Exploit Taxonomy

Category 1: Reentrancy

Pattern: External call before state update. Attacker's fallback/receive re-enters. Fix: CEI pattern, ReentrancyGuard, transient storage locks (EIP-1153). Detection: Slither reentrancy-eth, manual trace of all external calls.

Category 2: Flash Loan + Oracle Manipulation

Pattern: Borrow large amount → manipulate price in one block → profit from manipulated price → repay. Fix: TWAP oracles, Chainlink (multi-source), multi-block validation, circuit breakers. Detection: Check if any pricing function uses spot price from a single DEX.

Category 3: Bridge Exploits

Pattern: Trust assumption failure in the off-chain component. Fix: Minimize trust, use native rollup bridges, require high validator thresholds, monitoring + circuit breakers.

Category 4: Access Control / Logic

Pattern: Missing access control, unprotected initializers, key management failure. Fix: OZ AccessControl, initializer modifier, _disableInitializers(), hardware wallets, no vanity addresses.

Category 5: Precision / Math

Pattern: Integer division truncation, rounding in attacker's favor, compounding precision errors. Fix: Virtual shares (OZ 4.9+), multiply before divide, round in protocol's favor, use WAD math.

Foundry Fork Test Reproduction Template

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import {Test, console2} from "forge-std/Test.sol";
import {IERC20} from "forge-std/interfaces/IERC20.sol";

contract ExploitReproduction is Test {
    // Fork at the block BEFORE the exploit
    uint256 constant FORK_BLOCK = 15_000_000;
    string constant RPC = "https://eth-mainnet.g.alchemy.com/v2/KEY";

    // Addresses involved
    address constant VICTIM_CONTRACT = 0x1234...;
    address constant ATTACKER = 0xAttacker...;
    address constant USDC = 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48;

    function setUp() public {
        vm.createSelectFork(RPC, FORK_BLOCK);
    }

    function test_exploit() public {
        // 1. Set up attacker
        vm.startPrank(ATTACKER);
        vm.deal(ATTACKER, 100 ether);

        // 2. Log state before
        uint256 victimBalBefore = IERC20(USDC).balanceOf(VICTIM_CONTRACT);
        console2.log("Victim balance before:", victimBalBefore);

        // 3. Execute exploit steps
        // Step 1: Flash loan
        // Step 2: Manipulate price
        // Step 3: Exploit vulnerability
        // Step 4: Repay flash loan

        // 4. Log state after
        uint256 victimBalAfter = IERC20(USDC).balanceOf(VICTIM_CONTRACT);
        uint256 attackerProfit = IERC20(USDC).balanceOf(ATTACKER);
        console2.log("Victim balance after:", victimBalAfter);
        console2.log("Attacker profit:", attackerProfit);

        // 5. Assert the exploit worked
        assertGt(attackerProfit, 0, "Exploit should be profitable");
        assertLt(victimBalAfter, victimBalBefore, "Victim should lose funds");

        vm.stopPrank();
    }
}

Exploit Pattern Library (Audit Checklist)

DeFiHackLabs Study Guide

Located at: /data/.openclaw/workspace-chain/repos/DeFiHackLabs/

Study order (most educational exploits first):

1. Euler Finance (flash loan + donation attack)
2. Curve/Vyper reentrancy (compiler bug)
3. Nomad Bridge (initialization bug)
4. Mango Markets (oracle manipulation)
5. Cream Finance (read-only reentrancy)
6. Harvest Finance (flash loan + Curve manipulation)
7. bZx (first flash loan attack)
8. Compound governance (bad proposal)
9. Audius (uninitialized proxy)
10. Parity Multisig (access control)
11. First depositor attacks (ERC-4626)
12. Balancer (deflationary token + flash loan)
13. Wintermute (vanity address weakness)
14. Wormhole (signature verification bypass)
15. Ronin Bridge (key management failure)

For each: read the code, understand the bug, run the reproduction, write the fix.