Security Reviewer

Security Reviewer Skill

Core Philosophy

"Assume compromise; verify trust boundaries and input handling."

Focus on exploitable issues and insecure patterns. Prioritize by impact and likelihood.

Scope Boundary: Security-reviewer owns vulnerabilities, authentication/authorization, cryptography, sensitive data exposure, injection, and security configuration. For correctness, readability, maintainability, and code conventions, defer to the code-reviewer skill.

Protocol

1. Scope

• Identify trust boundaries (user input, network, filesystem, third-party services, cloud services).
• Trace sensitive data (secrets, tokens, PII, financial data, health data) from source to sink.
• Check for data leakage in logs, errors, debug endpoints, and API responses.
• Review authentication, authorization, and session handling.
• Assess injection points and unsafe deserialization.
• Evaluate file upload/download security.
• Check cryptographic implementations and key management.
• Review API security and rate limiting.
• Assess third-party dependency vulnerabilities.

2. Common Vulnerability Classes

See VULNERABILITIES.md for comprehensive reference of 27 vulnerability classes including:

• Injection (SQL, NoSQL, Command, XSS)
• Authentication/Authorization (IDOR, privilege escalation)
• Data Leaks (logs, errors, stack traces)
• Cryptography (weak algorithms, hardcoded keys)
• Configuration (debug mode, CORS, security headers)
• API Security (missing auth, over-fetching)
• And 21 more classes...

3. Severity

• Critical – Direct path to compromise or data breach; fix before release.
• High – Significant risk; should be fixed or explicitly accepted with mitigation.
• Medium – Moderate risk; should be addressed but may be deferred with mitigation.
• Low / Info – Minor risk or informational; good to fix but not blocking.

4. Output Format

## Summary
[Brief overview of findings]

## Critical
- **[Title]** - [Location] - [Description and remediation]

## High
- **[Title]** - [Location] - [Description and remediation]

## Medium
- **[Title]** - [Location] - [Description and remediation]

## Low / Info
- **[Title]** - [Location] - [Description and remediation]

## Positive notes (optional)
- [Security practices done well]

Reference Documents

For detailed information, see:

• VULNERABILITIES.md - 27 vulnerability classes with detection patterns
• SEARCH_PATTERNS.md - Grep/search patterns for security-relevant code
• DATA_LEAKS.md - Comprehensive data leak detection guide (IDOR, multi-tenant, logging, API responses)
• CHECKLIST.md - Complete security review checklist (13 categories)

Quick Start

1. Identify Trust Boundaries

Map where untrusted data enters the system:

• User input (forms, APIs, query params, headers)
• File uploads
• Network requests
• Third-party integrations

2. Trace Sensitive Data

Follow secrets, PII, tokens from source to sink:

• Are they logged?
• Exposed in errors?
• Stored securely?
• Encrypted in transit/at rest?

3. Check Authorization

Test access control:

• Can User A access User B's data (IDOR)?
• Are admin endpoints protected?
• Do GraphQL resolvers validate ownership?

Multi-tenant systems: Verify ALL queries include tenant_id filter.

See DATA_LEAKS.md for complete testing strategy.

4. Search for Patterns

Use grep/ripgrep to find security-relevant code:

# Secrets
grep -ri "password\|secret\|api_key\|token" .

# Injection
grep -ri "execute\|query\|SQL\|WHERE\|SELECT" .

# XSS
grep -ri "innerHTML\|dangerouslySetInnerHTML" .

See SEARCH_PATTERNS.md for complete search commands.

5. Review Findings Against Checklist

Use CHECKLIST.md to ensure comprehensive coverage:

• Input & trust boundaries
• Data protection
• Authentication & authorization
• Injection & code execution
• API & network security
• Cryptography
• Configuration
• Dependencies
• Multi-tenant isolation (if applicable)

Common Vulnerability Classes (Quick Reference)

See VULNERABILITIES.md for complete reference (27 classes).

Data Leak Detection (Critical)

Data leaks are the most common security issue. Check:

1. Unauthorized access - IDOR vulnerabilities
2. Multi-tenant isolation - Tenant A accessing Tenant B's data
3. Logging - Secrets, PII in logs
4. API responses - Over-fetching, internal fields
5. Error messages - Stack traces, verbose errors
6. Frontend - Secrets in JS bundles, console.log

See DATA_LEAKS.md for:

• 9 data leak vectors
• Detection strategy (10-step process)
• Remediation patterns
• Multi-tenant isolation best practices

Search Patterns (Quick Reference)

# Secrets
grep -ri "password\|secret\|api_key\|token\|credentials" .

# Data leaks
grep -ri "console.log\|printStackTrace\|error.stack" .

# Injection
grep -ri "execute\|eval\|exec\|query\|SQL" .

# XSS
grep -ri "innerHTML\|dangerouslySetInnerHTML\|v-html" .

# Authorization
grep -ri "user_id\|userId\|owner_id\|tenant_id" .

See SEARCH_PATTERNS.md for complete patterns by category.

Standards Reference

• OWASP Top 10 2021
• OWASP API Security Top 10
• CWE Top 25 Most Dangerous Software Weaknesses
• Project-specific security documentation or threat model

Checklist

Before completing security review, verify:

• Trust boundaries identified and validated
• Sensitive data flow traced (no leaks in logs/errors)
• Authorization enforced on all operations (IDOR checked)
• Injection vulnerabilities prevented
• API security reviewed (rate limiting, SSRF)
• Cryptography uses strong algorithms
• Configuration secure (no debug mode in prod)
• Dependencies scanned for vulnerabilities
• Multi-tenant isolation verified (if applicable)
• Findings include severity and remediation

See CHECKLIST.md for complete 13-category checklist.

Cross-Skill Integration