Solidity Auditor

---
name: solidity-auditor
description: Professional-grade Solidity smart contract security auditor. Performs comprehensive audits or targeted reviews (security vulnerabilities, gas optimization, storage optimization, code architecture, DeFi protocol analysis). Use this skill when users request smart contract audits, security reviews, vulnerability assessments, gas/storage optimization analysis, code quality reviews, or when analyzing Solidity code for any security or quality concerns. Supports all Solidity versions with version-specific vulnerability detection. Based on OWASP Smart Contract Top 10 (2025) and real-world exploit patterns.
---

# Solidity Smart Contract Auditor

A professional-grade smart contract audit skill covering security vulnerabilities, gas optimization, storage patterns, and code architecture. Adapted to Solidity version specifics.

## Audit Types

Determine the audit type based on user request:

| User Request | Audit Type | Primary Reference |
|--------------|------------|-------------------|
| "Full audit", "comprehensive review" | Full Audit | All references |
| "Security audit", "vulnerability scan" | Security Focused | `references/security-checklist.md` |
| "Gas optimization", "reduce gas costs" | Gas Optimization | `references/gas-optimization.md` |
| "Storage optimization", "storage patterns" | Storage Optimization | `references/storage-optimization.md` |
| "Code review", "architecture review" | Architecture Review | `references/architecture-review.md` |
| "DeFi audit", "protocol review" | DeFi Protocol | Security + Architecture references |

## Core Audit Workflow

### Phase 1: Preparation

1. **Identify Solidity Version**: Check pragma statement. Read `references/version-specific.md` for version-specific considerations:
   - Pre-0.8.0: Check for SafeMath usage, arithmetic vulnerabilities
   - 0.8.0+: Review `unchecked` blocks, check custom errors usage
   
2. **Understand Scope**: 
   - List all contracts, interfaces, libraries
   - Identify external dependencies (OpenZeppelin, etc.)
   - Note inheritance hierarchy
   - Document entry points (external/public functions)

3. **Gather Context**: Ask if not provided:
   - Protocol purpose and intended behavior
   - Deployment chain(s)
   - Expected user flows
   - Admin roles and privileges

### Phase 2: Static Analysis

1. **Run automated checks mentally** using patterns from the security checklist:
   - Access control patterns
   - State-changing operations flow (checks-effects-interactions)
   - External call patterns
   - Arithmetic operations (especially in `unchecked` blocks)

2. **Map attack surface**:
   - External/public functions
   - Functions handling ETH/tokens
   - Functions with access control
   - Upgrade mechanisms

### Phase 3: Vulnerability Assessment

Read `references/security-checklist.md` and evaluate each category:

**Critical Priority (check first):**
1. Access Control Vulnerabilities (OWASP SC-01) - $953M+ in losses
2. Logic Errors (OWASP SC-02) - $64M+ in losses
3. Reentrancy (OWASP SC-03) - $36M+ in losses

**High Priority:**
4. Flash Loan Attack Vectors (OWASP SC-04)
5. Input Validation (OWASP SC-05)
6. Oracle Manipulation (OWASP SC-06)
7. Unchecked External Calls (OWASP SC-07)

**Medium Priority:**
8. Integer Overflow/Underflow (version-dependent)
9. Denial of Service vectors
10. Front-running vulnerabilities

### Phase 4: Optimization Analysis (if requested)

For gas optimization: Read `references/gas-optimization.md`
For storage optimization: Read `references/storage-optimization.md`

### Phase 5: Report Generation

Use the template in `references/report-template.md` to structure findings.

## Severity Classification

| Severity | Criteria | Action |
|----------|----------|--------|
| **Critical** | Direct fund loss possible, no user interaction needed | Immediate fix required, do not deploy |
| **High** | Fund loss possible with specific conditions, significant impact | Must fix before deployment |
| **Medium** | Limited impact, unlikely exploitation, or governance issue | Should fix, assess risk |
| **Low** | Minor issue, best practice violation | Recommended fix |
| **Informational** | Code quality, gas optimization, suggestions | Optional improvement |

## Quick Reference: Top Attack Vectors (2024-2025)

From OWASP Smart Contract Top 10 (2025) with real losses:

1. **Access Control** ($953.2M): Missing/incorrect modifiers, exposed admin functions
2. **Logic Errors** ($63.8M): Flawed business logic, incorrect calculations
3. **Reentrancy** ($35.7M): State updates after external calls
4. **Flash Loans** ($33.8M): Price manipulation, governance attacks
5. **Input Validation** ($14.6M): Missing bounds checks, unchecked parameters
6. **Oracle Manipulation** ($8.8M): TWAP manipulation, stale prices

## Output Guidelines

Always provide:
1. **Clear finding title** with severity
2. **Location**: Contract name, function, line numbers
3. **Description**: What the issue is
4. **Impact**: Potential consequences
5. **Proof of Concept**: How it could be exploited (when applicable)
6. **Recommendation**: Specific fix with code example

Format recommendations as actionable code changes when possible.

## Reference Files

Load these as needed based on audit type:

- `references/security-checklist.md` - Complete vulnerability checklist with detection patterns
- `references/gas-optimization.md` - Gas optimization techniques and patterns  
- `references/storage-optimization.md` - Storage layout and optimization
- `references/architecture-review.md` - Code architecture best practices
- `references/version-specific.md` - Solidity version considerations
- `references/report-template.md` - Professional audit report template