Mastering Smart Contract Security: A 12-Step Audit Workflow for Developers

The workflow installs the toolchain, runs Slither static analysis, fuzzes with Foundry, and ends with proof-of-concept exploits against a contract seeded with known bugs.

The timing is not cosmetic. Chainalysis figures put Truebit at $26.2 million lost on January 8 to an integer overflow in a bonding curve. Trusted Volumes lost $5.9 million in May to an access control flaw in a swap proxy. Aperture Finance lost $3.2 million in January to an input validation bypass on a raw transferFrom call. Ekubo lost $1.4 million in May because a callback never checked who the payer actually was. None of these are exotic. A structured audit catches every one.

The pipeline

The tutorial frames audit as a process. Static analysis first — Slither against all detectors, treating each finding as a stop-the-line item. Foundry fuzzing next, targeting protocol invariants under heavy state mutation. Then a manual pass on business logic. Then a second set of eyes.

Each stage hits a different class of bug. Slither catches reentrancy, unchecked return values, uninitialized storage. Foundry surfaces invariant violations that a 2,000-line file hides from human review. The manual pass addresses what scanners cannot parse: flawed oracle assumptions, mispriced flash loan callbacks, privileged role escalation paths.

Ninety minutes is unrealistic for production code. What the tutorial actually delivers is a triage workflow. Fast enough to run on every pull request. Rigorous enough to catch the shallow bugs that dominate post-mortems.

Context: the threat surface shifted

AI-assisted fuzzers now scan live bytecode within hours of deployment, per a 2026 Hive Project write-up. Reentrancy, oracle manipulation, and upgrade-proxy logic errors sit at roughly 41% of 2026 DeFi losses combined. Attackers specifically hunt unverified contracts, betting the deployer skipped review.

The same week, ethereum.org added a Foundry Fundamentals course covering Forge and Anvil. KuCoin published a guide on reentrancy, flash loan oracle manipulation, and cross-chain bridge vulnerabilities. ForkLog analyzed the shift from manual hacking to agentic, AI-driven exploits. The defender stack is catching up. Slowly.

Pre-deploy audit checklist

Run before mainnet:

• Slither with all detectors enabled. Zero unaddressed findings.
• Foundry invariant suite. Minimum three protocol invariants. Fuzz for 10,000+ runs.
• Manual access control trace. Every privileged function mapped. Role separation verified.
• Flash loan callback review. Caller validated on every external hook.
• Upgrade proxy inspection. Storage layout confirmed. Timelock on admin.
• Independent reviewer. No self-approval. No exceptions.