How to Recover Hacked Yield Farming Funds: Emergency Response Guide

// Vulnerable yield farming contract example
contract VulnerableYieldFarm {
    mapping(address => uint256) public deposits;
    
    function withdraw(uint256 amount) external {
        require(deposits[msg.sender] >= amount, "Insufficient balance");
        
        // VULNERABILITY: External call before state update
        (bool success, ) = msg.sender.call{value: amount}("");
        require(success, "Transfer failed");
        
        deposits[msg.sender] -= amount; // State update after external call
    }
}

# Quick blockchain analysis commands
# Check recent transactions
curl -X GET "https://api.etherscan.io/api?module=account&action=txlist&address=YOUR_WALLET&startblock=0&endblock=99999999&sort=desc&apikey=YOUR_API_KEY"

# Analyze token transfers
curl -X GET "https://api.etherscan.io/api?module=account&action=tokentx&address=YOUR_WALLET&startblock=0&endblock=99999999&sort=desc&apikey=YOUR_API_KEY"

// Check token approvals
async function checkApprovals(walletAddress) {
    const approvals = await fetch(`https://api.etherscan.io/api?module=account&action=tokentx&address=${walletAddress}&apikey=YOUR_API_KEY`);
    const data = await approvals.json();
    
    // Filter for approval transactions
    const approvalTxs = data.result.filter(tx => 
        tx.input.startsWith('0x095ea7b3') // approve function selector
    );
    
    console.log('Active approvals:', approvalTxs);
}

# Python script for basic fund tracing
import requests
import json

def trace_funds(tx_hash, depth=5):
    """Trace stolen funds through blockchain transactions"""
    
    # Get transaction details
    url = f"https://api.etherscan.io/api?module=proxy&action=eth_getTransactionByHash&txhash={tx_hash}&apikey=YOUR_API_KEY"
    response = requests.get(url)
    tx_data = response.json()['result']
    
    # Extract recipient address
    recipient = tx_data['to']
    
    # Get recipient's transaction history
    history_url = f"https://api.etherscan.io/api?module=account&action=txlist&address={recipient}&apikey=YOUR_API_KEY"
    history_response = requests.get(history_url)
    transactions = history_response.json()['result']
    
    # Analyze fund flow patterns
    for tx in transactions[:depth]:
        print(f"Transaction: {tx['hash']}")
        print(f"Value: {int(tx['value']) / 1e18} ETH")
        print(f"To: {tx['to']}")
        print("---")

# Usage
trace_funds("0x1234567890abcdef...")

// MEV recovery contract
contract MEVRecovery {
    address public owner;
    address public targetWallet;
    
    constructor(address _targetWallet) {
        owner = msg.sender;
        targetWallet = _targetWallet;
    }
    
    function frontRunRecovery() external payable {
        require(msg.sender == owner, "Only owner");
        
        // Monitor target wallet for outgoing transactions
        // Submit higher gas price transaction to recover funds
        // This requires sophisticated MEV infrastructure
    }
}

// Cross-chain tracking script
async function trackCrossChain(address) {
    const chains = ['ethereum', 'polygon', 'arbitrum', 'optimism'];
    const results = {};
    
    for (const chain of chains) {
        const balance = await getBalance(address, chain);
        const transactions = await getTransactions(address, chain);
        
        results[chain] = {
            balance,
            recentTransactions: transactions.slice(0, 10)
        };
    }
    
    return results;
}

// Security checklist for yield farming contracts
contract SecurityChecklist {
    // ✓ Reentrancy protection
    bool private locked;
    
    modifier noReentrant() {
        require(!locked, "ReentrancyGuard: reentrant call");
        locked = true;
        _;
        locked = false;
    }
    
    // ✓ Safe math operations
    using SafeMath for uint256;
    
    // ✓ Access control
    modifier onlyOwner() {
        require(msg.sender == owner, "Not authorized");
        _;
    }
    
    // ✓ Emergency pause mechanism
    bool public paused = false;
    
    modifier whenNotPaused() {
        require(!paused, "Contract is paused");
        _;
    }
}

// Multi-signature wallet setup
const multisigWallet = await ethers.getContractFactory("MultiSigWallet");
const wallet = await multisigWallet.deploy(
    [owner1, owner2, owner3], // signers
    2 // required confirmations
);

// Secure yield farming deposit
async function secureDeposit(amount, farmContract) {
    const tx = await wallet.submitTransaction(
        farmContract.address,
        0,
        farmContract.interface.encodeFunctionData("deposit", [amount])
    );
    
    // Requires 2 out of 3 signatures to execute
    await wallet.confirmTransaction(tx.hash);
}

def assess_farm_risk(protocol_data):
    """Calculate risk score for yield farming protocols"""
    
    risk_factors = {
        'tvl': protocol_data['total_value_locked'],
        'audit_score': protocol_data['security_audits'],
        'time_deployed': protocol_data['days_since_launch'],
        'team_reputation': protocol_data['team_score']
    }
    
    # Calculate weighted risk score
    weights = {'tvl': 0.3, 'audit_score': 0.4, 'time_deployed': 0.2, 'team_reputation': 0.1}
    risk_score = sum(risk_factors[factor] * weights[factor] for factor in risk_factors)
    
    return min(risk_score, 100)  # Cap at 100

// Anti-sandwich recovery contract
contract SandwichRecovery {
    mapping(bytes32 => bool) public processedTxs;
    
    function recoverSandwichedFunds(
        bytes32 originalTxHash,
        address victim,
        uint256 expectedAmount
    ) external {
        require(!processedTxs[originalTxHash], "Already processed");
        
        // Analyze transaction for sandwich attack patterns
        // Calculate MEV extracted
        // Compensate victim from recovered funds
        
        processedTxs[originalTxHash] = true;
    }
}

// Automated monitoring system
class YieldFarmMonitor {
    constructor(walletAddress, protocolAddresses) {
        this.wallet = walletAddress;
        this.protocols = protocolAddresses;
        this.alerts = [];
    }
    
    async monitorTransactions() {
        const web3 = new Web3(process.env.RPC_URL);
        
        // Monitor for suspicious activities
        web3.eth.subscribe('pendingTransactions', (error, txHash) => {
            if (error) console.error(error);
            
            this.analyzePendingTransaction(txHash);
        });
    }
    
    async analyzePendingTransaction(txHash) {
        const tx = await web3.eth.getTransaction(txHash);
        
        // Check for flash loan patterns
        if (this.isFlashLoanAttack(tx)) {
            this.sendAlert('Flash loan attack detected!');
        }
        
        // Monitor large withdrawals
        if (this.isLargeWithdrawal(tx)) {
            this.sendAlert('Large withdrawal detected');
        }
    }
}

# Automated emergency response system
class EmergencyResponse:
    def __init__(self, wallet_private_key):
        self.wallet = wallet_private_key
        self.emergency_actions = []
    
    def detect_hack(self, transaction_data):
        """Detect potential hack based on transaction patterns"""
        
        suspicious_patterns = [
            'large_unexpected_withdrawal',
            'multiple_approval_transactions',
            'interaction_with_unknown_contracts'
        ]
        
        for pattern in suspicious_patterns:
            if self.pattern_matches(transaction_data, pattern):
                self.execute_emergency_response()
                break
    
    def execute_emergency_response(self):
        """Execute pre-programmed emergency actions"""
        
        # 1. Revoke all token approvals
        self.revoke_all_approvals()
        
        # 2. Transfer remaining funds to secure wallet
        self.emergency_transfer()
        
        # 3. Send alerts to monitoring services
        self.send_alerts()