Web3 Security Audit Checklist for Smart Contracts

Pre-Audit Preparation

Before submitting for audit, prepare your codebase thoroughly. Professional auditors expect well-documented, tested code.

Documentation requirements:
Clear README explaining project purpose
Architecture overview and design decisions
Function documentation with NatSpec
Known issues and assumptions
Deployment procedures

Code quality:
Follow style guides consistently
Remove dead code and comments
Organize files logically
Use meaningful variable names
Implement proper error messages

Testing coverage:
Unit tests for all functions
Integration tests for workflows
Edge case testing
Fuzz testing results
Code coverage reports

The better prepared you are, the more value you'll get from the audit.

Common Vulnerability Checklist

Reentrancy:
Check all external calls
Use ReentrancyGuard where needed
Follow Checks-Effects-Interactions pattern
Test with malicious contracts

Access Control:
Verify all privileged functions protected
Check for missing modifiers
Test unauthorized access attempts
Validate role assignments

Integer Issues:
Use Solidity 0.8+ for overflow protection
Verify SafeMath in older versions
Check for underflow in subtraction
Test boundary conditions

Front-Running:
Identify vulnerable functions
Implement commit-reveal if needed
Use slippage protection
Consider MEV implications

Oracle Manipulation:
Validate oracle data freshness
Use multiple oracle sources
Implement circuit breakers
Test with extreme values

Flash Loan Attacks:
Identify flash loan vulnerable logic
Add flash loan protection
Test with flash loan scenarios
Consider economic attacks

Smart Contract Best Practices

Code organization:
Separate concerns clearly
Use inheritance appropriately
Limit contract size
Modularize complex logic

State management:
Minimize storage usage
Use appropriate data types
Implement storage gaps for upgrades
Document storage layout

Error handling:
Use require for validation
Use revert with custom errors
Provide clear error messages
Handle all failure cases

Gas optimization:
Profile gas usage
Optimize hot paths
Use appropriate data structures
Batch operations when possible

Events and logging:
Emit events for all state changes
Include relevant data in events
Use indexed parameters appropriately
Document event purposes

External calls:
Validate addresses before calling
Handle call failures
Use appropriate call methods
Limit trust in external contracts

Testing and Verification

Comprehensive testing:
Test all functions thoroughly
Include negative test cases
Test access controls
Verify event emissions
Test upgrade mechanisms
Simulate attack scenarios

Automated analysis:
Run Slither for static analysis
Use Mythril for symbolic execution
Check with Securify
Run Echidna for fuzzing
Analyze with Manticore

Manual review:
Code walkthrough with team
Peer review by other developers
Security-focused code review
Logic verification
Economic model validation

Testnet deployment:
Deploy to testnet first
Test all functionality
Simulate real usage
Monitor for issues
Gather user feedback

Mainnet preparation:
Final security review
Deployment checklist
Monitoring setup
Incident response plan
Communication strategy

Post-Audit Actions

Address audit findings:
Fix critical issues immediately
Resolve high severity issues
Consider medium severity recommendations
Document decisions on low severity items

Verification:
Verify fixes address issues
Re-test affected functionality
Consider re-audit for major changes
Update documentation

Deployment:
Use audited code exactly
Verify contract addresses
Test deployment on testnet first
Implement monitoring
Prepare for emergencies

Ongoing security:
Monitor for unusual activity
Keep dependencies updated
Engage with security community
Maintain bug bounty program
Regular security reviews

Transparency:
Publish audit reports
Communicate findings to community
Document security measures
Share lessons learned

Security is ongoing, not one-time. Maintain vigilance and adapt to new threats as they emerge.