
1) Audit Objectives (what “secure” really means)
- Safety: no loss of funds, no stuck funds, no griefing.
- Liveness: protocol can progress (no perma-pauses, deadlocks).
- Economic soundness: incentive compatibility, oracle & MEV resilience.
- Governance safety: upgrade, pause, and treasury powers are bounded, transparent, and time-locked.
- Operational resilience: monitoring, incident response, and key management exist and are tested.
2) Pre-Audit Readiness (save 30–50% audit time)
- Freeze scope + tag: commit hash, compiler version, networks, dependencies.
- Threat model: actors (user, LP, keeper, governor), trust assumptions, invariants (e.g., total supply, collateralization).
- Docs: architecture, state machines, role matrix, admin runbooks, upgradability plan.
- Tests ≥ 95% critical paths: unit + integration + fuzz; include invariants.
- Static analyzers clean: Slither, Mythril, Semgrep, Solhint.
- Gas profiling: ensure no DoS-by-gas surprises.
3) Auditor Workflow (what we actually do)
- Recon: map contracts, storage, privileges, upgrade/proxy layout.
- Static analysis & linters: triage smells and anti-patterns.
- Manual review: line-by-line with invariants at hand.
- Property testing / fuzzing: Foundry/echidna invariants; randomized sequences.
- Economic & oracle review: price manipulation, TWAP windows, liquidity depth.
- Governance checks: timelocks, emergency stops, access control, multisig thresholds.
- Post-audit validation: fixes re-checked; diff-based final pass.
4) Top Vulnerability Classes (and quick fixes)
- Reentrancy: use
checks-effects-interactions,ReentrancyGuard, pull payments; avoid untrusted callbacks before state updates. - Access control drift: centralize with
onlyRole, explicit role docs,AccessControl, timelocks for sensitive ops. - Math/precision: use
uncheckedonly with proofs; prefermulDiv(full-precision), validate rounding. - Oracle manipulation: use medianizers/TWAP; require min liquidity & staleness checks; fail closed on bad feeds.
- Upgrade/proxy bricking: lock implementation; transparent vs UUPS correctly; restrict upgrade to multisig + timelock.
- Allowance race (ERC-20): recommend
increaseAllowance/permit; zero-first pattern in UIs. - Unchecked external calls: validate return values; limit gas stipends; whitelist targets if using
call. - Signature replay: include chainId, domain separators, nonces; expire signatures.
- Denial-of-Service by loops: cap loop length; use mappings/queues; batch with bounds.
- Front-running / MEV: commit-reveal, cool-downs, slippage bounds, uniform clearing auctions where feasible.
- Bridge & cross-chain: verify message origin, replay protection, rate-limits, emergency circuit-breakers.
5) Secure Solidity Patterns (mini-snippets)
Access control + timelocked upgrade
contract Governed is AccessControl {
bytes32 public constant GOV = keccak256("GOV");
TimelockController public immutable timelock;
constructor(address _multisig, uint256 delay)
{ _grantRole(GOV, _multisig); timelock = new TimelockController(delay, [_multisig], [_multisig]); }
function upgrade(address newImpl) external onlyRole(GOV) {
require(timelock.isOperationReady(keccak256(abi.encode(newImpl))), "TL!");
_upgradeTo(newImpl);
}
}
Oracle sanity checks
function _readPrice() internal view returns (uint256 px) {
(, int256 ans,, uint256 updatedAt,) = feed.latestRoundData();
require(updatedAt + 30 minutes >= block.timestamp, "STALE");
require(ans > 0, "NEG");
px = uint256(ans);
require(px >= MIN_PX && px <= MAX_PX, "OOB");
}
Pull-payment to avoid reentrancy
mapping(address=>uint256) public credits;
function withdraw() external nonReentrant {
uint256 amt = credits[msg.sender];
credits[msg.sender] = 0;
(bool ok,) = msg.sender.call{value: amt}("");
require(ok,"XFER");
}
6) Testing That Catches Real Bugs
- Foundry fuzz invariants: balances never negative; sum of shares == total; collateral ratio ≥ MCR.
- Property examples: “redeem then deposit leaves totalSupply unchanged”, “fees ≤ cap”, “oracle update never decreases timestamp”.
- Differential testing: compare against reference AMM/math lib (e.g., Uniswap v2/v3 libraries).
- Fork-tests: simulate mainnet liquidity/MEV; attempt sandwich, oracle skew, flash-loan manipulations.
7) Upgrades, Pauses & Incident Response
- Multisig + timelock: upgrades, parameter changes. Emergencies can pause, but unpause via timelock.
- Runbooks: who pages whom; T-0 containment, T-1h comms, T-24h post-mortem outline.
- Kill-switch scope: pause trading but allow withdrawals if safe; pre-commit policy in docs.
8) Monitoring & On-chain Alerts
- Health checks: watchdog for price staleness, reserves deltas, abnormal mint/burn.
- Alerts: large transfers, admin calls, upgrade events, pauser triggers.
- Analytics: Dune/Nansen dashboards; invariant drift alarms.
- Off-chain logs: ship node + relayer logs to SIEM; keep chain reorg awareness.
9) Bug Bounty & Responsible Disclosure
- Launch after audit; tiered rewards, on-chain program link, clear SLA.
- Safe harbor language; exclude known “intended behavior” with examples.
- Pay promptly; publish anonymized write-ups to improve community safety.
10) Vendor & Tooling (starter stack)
- Static/linters: Slither, Solhint/Semgrep.
- Fuzz/property: Foundry (invariant), Echidna.
- Formal methods (selective): Certora/SMTChecker for core invariants.
- SCA & deps: npm/yarn audit + lockfile pinning; verify libraries.
- Secrets: SOPs for deployer keys, hardware wallets, shard + multisig.
11) Launch Checklist
- Commit/compile pinned; reproducible builds.
- All high/critical audit findings fixed & re-verified.
- Admin roles: multisig + timelock live; EOA keys removed.
- Oracles: TWAP/median + staleness guards.
- Pauser tested on-chain; withdrawal policy documented.
- Monitor + alerting dashboards online.
- Bug bounty live; response runbook rehearsed.
- Public docs: risks, parameters, upgrade & governance policies.
Quick FAQ
- Single vs multi-auditor? Prefer at least two independent reviews for core protocols.
- Formal verification? Use selectively for components with simple, critical invariants (vault accounting, AMM math).
- Are testnets enough? No. Use testnets + mainnet forks + chaos scenarios.
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