Skill Guide

Smart contract auditing in Solidity, Vyper, and Rust (Solana/Aptos)

Smart contract auditing is the systematic, security-focused analysis of blockchain contract code-written in Solidity, Vyper, or Rust-to identify vulnerabilities, logic errors, and economic exploits before deployment.

It directly mitigates catastrophic financial loss and reputational damage for protocols handling millions in user funds. Audited contracts are a non-negotiable baseline for user trust and institutional adoption in DeFi and Web3.

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How to Learn Smart contract auditing in Solidity, Vyper, and Rust (Solana/Aptos)

Solidify core blockchain fundamentals: consensus, gas, state management. Master the syntax and common security pitfalls of Solidity (reentrancy, integer overflow/underflow). Study the EVM's storage layout and execution model at the bytecode level.

Transition to active vulnerability hunting on testnets or past hack repositories (e.g., Rekt.news, Immunefi). Master automated tooling (Slither, Mythril, Echidna) and manual review of complex, multi-contract systems. Learn to write proof-of-concept (PoC) exploits.

Develop expertise in complex attack vectors: flash loan oracle manipulation, cross-chain bridge logic flaws, and DAO governance attacks. Master Rust security for Solana/Aptos (ownership/borrowing model, PDA vulnerabilities). Architect secure patterns and conduct economic invariant analysis.

Practice Projects

Beginner

Project

Audit a Standard ERC-20 Token Contract

Scenario

You are given a simplified ERC-20 token contract with known, classic vulnerabilities (e.g., lack of checks-effects-interactions, public burn function).

How to Execute

1. Manually trace all state changes and external calls. 2. Use Slither to run a static analysis and map the output to your manual findings. 3. Document each vulnerability (CWE/Severity) and write a concrete mitigation code fix. 4. Write a simple Hardhat test to verify the exploit and the fix.

Intermediate

Project

Analyze a Live DeFi Vault's Withdrawal Logic

Scenario

Audit a yield-bearing vault contract where the share price calculation might be manipulable via a flash loan in the same transaction block.

How to Execute

1. Map the entire deposit/withdraw flow, focusing on when the balance is read and the share price is calculated. 2. Use Foundry's fuzz testing to simulate a sequence: user deposit -> attacker flash loan & manipulate price -> user withdraw at incorrect price. 3. Write the test case that proves the invariant (share_price * total_shares == total_balance) can be broken. 4. Propose and implement the fix using a time-weighted average price (TWAP) or a request-fulfillment pattern.

Advanced

Project

Audit a Cross-Chain Bridge's Message Validation

Scenario

Audit a bridge contract where Rust code on Solana (Aptos/Move for advanced track) validates messages from an EVM chain. The core risk is a signature verification flaw or a replay attack.

How to Execute

1. Perform a deep dive into the message serialization/deserialization on both chains (EVM ABI vs. BCS for Move). 2. Analyze the signature scheme (ECDSA secp256k1 vs. ed25519) and the nonce/replay protection mechanism. 3. Use formal verification tools (e.g., Move Prover, Certora) to mathematically prove the liveness and safety properties of the validation logic. 4. Write a comprehensive threat model covering insider key compromise, validator collusion, and sequencer failure.

Tools & Frameworks

Static Analysis & Automated Detection

SlitherMythrilSemgrep

First-pass tools to detect common vulnerability patterns (reentrancy, unsafe math) and code smells. Run on every commit in CI/CD.

Dynamic Analysis & Fuzzing

EchidnaFoundry FuzzManticore

Used to test contract invariants under adversarial, randomized inputs. Essential for finding logic bugs that static analysis misses.

Development & Testing Frameworks

Foundry (forge/cast)HardhatAnchor (for Solana)Aptos CLI/Move

Core environments for writing, deploying, and unit/fuzz testing contracts. Mastery of Foundry is a strong industry signal for EVM auditors.

Manual Review & Formal Methods

Certora ProverMove ProverManual Taint Analysis

The final, highest-assurance layer. Formal verification proves specific properties; manual analysis finds subtle business logic flaws.

Interview Questions

Answer Strategy

The candidate must demonstrate a structured audit methodology. Start with the proxy's storage layout collision risk. Then analyze the oracle's trust assumptions and attack vectors (stale data, single-source manipulation). Finally, connect the dots: how a malicious implementation upgrade could exploit the oracle dependency to drain funds. Use the 'People-Process-Technology' framework but apply it to 'Proxy-Oracle-Upgrade' logic.

Answer Strategy

Tests risk assessment and stakeholder management. The answer must show prioritization: a 'Critical' severity label regardless of likelihood. It should outline a clear, professional process: 1. Secure, encrypted disclosure to the core team. 2. Provide a precise PoC and patch. 3. Advise on a temporary mitigation (e.g., pause function) if possible. 4. Coordinate the upgrade announcement timeline to avoid tipping off attackers. This is a behavioral test for professionalism under pressure.