Security patterns for autonomous trading agents with wallet or transaction authority. Covers prompt injection, spend limits, pre-send simulation, circuit breakers, MEV protection, and key handling.
Autonomous trading agents have a harsher threat model than normal LLM apps: an injection or bad tool path can turn directly into asset loss.
Layer the defenses. No single check is enough. Treat prompt hygiene, spend policy, simulation, execution limits, and wallet isolation as independent controls.
import re
INJECTION_PATTERNS = [
r'ignore (previous|all) instructions',
r'new (task|directive|instruction)',
r'system prompt',
r'send .{0,50} to 0x[0-9a-fA-F]{40}',
r'transfer .{0,50} to',
r'approve .{0,50} for',
]
def sanitize_onchain_data(text: str) -> str:
for pattern in INJECTION_PATTERNS:
if re.search(pattern, text, re.IGNORECASE):
raise ValueError(f"Potential prompt injection: {text[:100]}")
return text
Do not blindly inject token names, pair labels, webhooks, or social feeds into an execution-capable prompt.
from decimal import Decimal
MAX_SINGLE_TX_USD = Decimal("500")
MAX_DAILY_SPEND_USD = Decimal("2000")
class SpendLimitError(Exception):
pass
class SpendLimitGuard:
def check_and_record(self, usd_amount: Decimal) -> None:
if usd_amount > MAX_SINGLE_TX_USD:
raise SpendLimitError(f"Single tx ${usd_amount} exceeds max ${MAX_SINGLE_TX_USD}")
daily = self._get_24h_spend()
if daily + usd_amount > MAX_DAILY_SPEND_USD:
raise SpendLimitError(f"Daily limit: ${daily} + ${usd_amount} > ${MAX_DAILY_SPEND_USD}")
self._record_spend(usd_amount)
class SlippageError(Exception):
pass
async def safe_execute(self, tx: dict, expected_min_out: int | None = None) -> str:
sim_result = await self.w3.eth.call(tx)
if expected_min_out is None:
raise ValueError("min_amount_out is required before send")
actual_out = decode_uint256(sim_result)
if actual_out < expected_min_out:
raise SlippageError(f"Simulation: {actual_out} < {expected_min_out}")
signed = self.account.sign_transaction(tx)
return await self.w3.eth.send_raw_transaction(signed.raw_transaction)
class TradingCircuitBreaker:
MAX_CONSECUTIVE_LOSSES = 3
MAX_HOURLY_LOSS_PCT = 0.05
def check(self, portfolio_value: float) -> None:
if self.consecutive_losses >= self.MAX_CONSECUTIVE_LOSSES:
self.halt("Too many consecutive losses")
if self.hour_start_value <= 0:
self.halt("Invalid hour_start_value")
return
hourly_pnl = (portfolio_value - self.hour_start_value) / self.hour_start_value
if hourly_pnl < -self.MAX_HOURLY_LOSS_PCT:
self.halt(f"Hourly PnL {hourly_pnl:.1%} below threshold")
import os
from eth_account import Account
private_key = os.environ.get("TRADING_WALLET_PRIVATE_KEY")
if not private_key:
raise EnvironmentError("TRADING_WALLET_PRIVATE_KEY not set")
account = Account.from_key(private_key)
Use a dedicated hot wallet with only the required session funds. Never point the agent at a primary treasury wallet.
import time
PRIVATE_RPC = "https://rpc.flashbots.net"
MAX_SLIPPAGE_BPS = {"stable": 10, "volatile": 50}
deadline = int(time.time()) + 60
min_amount_out is mandatory