Resilience and security auditing

Resilience and Security Auditing

This skill orchestrates a comprehensive audit of code focusing strictly on security, concurrency, data boundaries, and distributed systems resilience.

When to Use

• Use when handling user input, authentication, or authorization.
• Use when evaluating thread safety and concurrency models.
• Use when designing or modifying distributed/network systems.
• NOT for functional QA testing or visual UI reviews.

Core Process

Phase 1: Security & Defensive Programming

• Zero Trust Boundaries: Assume all inputs are malicious. Validate types, lengths, and formats.
• Least Privilege: Ensure the process runs with the minimum permissions required.
• Input Sanitization: Specifically test for SQLi, XSS, and path traversal vulnerabilities.
• Fail-Fast (FEAR): Throw explicit exceptions upon detecting invalid states immediately; do not attempt to silently recover corrupt state.

Phase 2: Resilience & Network Robustness

• Idempotency: Verify that mutative operations can be retried safely without side effects.
• Circuit Breakers: Ensure external API calls are wrapped in circuit breakers with timeouts and exponential backoff.
• Timeouts: No network call should execute indefinitely.

Phase 3: Concurrency Safety

• Immutability: Assert that shared data structures default to immutable.
• Pure Functions: Verify that concurrent executions do not mutate shared state without strict thread safety.

Common Rationalizations

Rationalization	Reality
"This input comes from our frontend, it's safe."	Frontend validation is purely cosmetic. The backend must enforce Zero Trust and re-validate everything.
"A timeout isn't necessary, the internal service is fast."	Internal networks partition and stall. Missing timeouts lead to catastrophic thread exhaustion.
"I'll sanitize inputs later."	Security cannot be bolted on. Inputs must be sanitized at the boundary layer.

Red Flags

• Network requests (fetch, axios, DB drivers) without explicit timeout arguments.
• Mutable shared state in highly concurrent contexts.
• Controller/API endpoints that blindly pass raw request bodies to the database layer.

Verification

Before passing the security audit, verify:

• All external dependencies and API calls possess explicit timeouts and retry mechanisms.
• User input boundaries perform explicit type and schema validation.
• Critical state updates are idempotent.
• Execution halts immediately (throw) upon detecting an invalid state.