Security Hardening

Security Hardening

Overview

Structured workflow to audit and harden security before any feature ships. Covers RLS policies, auth sessions, environment secrets, CSP headers, and rate limiting.

When to Use

• Before shipping ANY new table or feature to production
• After creating or modifying RLS policies
• When auditing authentication flow
• When rotating secrets or API keys
• When adding security headers

Workflow

Phase 1: RLS Audit

1. List all tables: SELECT tablename FROM pg_tables WHERE schemaname = 'public';
2. Verify RLS enabled: SELECT relname, relrowsecurity FROM pg_class WHERE relname = '<table>';
3. List policies: SELECT * FROM pg_policies WHERE tablename = '<table>';
4. Verify every policy uses auth.uid() for user isolation
5. Test: user A cannot read user B's data
6. Test: anonymous users get zero rows on protected tables

Pass: Every public table has RLS with SELECT + INSERT + UPDATE + DELETE policies using auth.uid().

Phase 2: Auth Session Hardening

1. Verify Supabase client has autoRefreshToken: true
2. Confirm <ProtectedRoute> wraps all authenticated pages in App.tsx
3. Check useAuth handles expired sessions (redirect to login)
4. Verify OAuth callback doesn't leak tokens in URL params
5. Confirm no session data in console.log or error messages

Phase 3: Environment & Secrets

1. Scan: grep -r "sk-\|sk_live\|SUPABASE_SERVICE" src/
2. Verify .env in .gitignore
3. Only VITE_SUPABASE_URL and VITE_SUPABASE_PUBLISHABLE_KEY exposed to client
4. Edge functions use Deno.env.get(), never hardcoded
5. No secrets in git history

Phase 4: Security Headers

1. Content-Security-Policy configured
2. X-Frame-Options: DENY
3. X-Content-Type-Options: nosniff
4. Referrer-Policy: strict-origin-when-cross-origin

Phase 5: Rate Limiting

1. Rate limits on public edge functions
2. Per-IP: 100 req/min API, 10/min auth
3. Return 429 with Retry-After header

Checklist

• All tables have RLS enabled
• All RLS policies use auth.uid()
• No cross-user data leakage
• Sessions auto-refresh, no tokens in URLs
• Zero hardcoded secrets in source
• .env in .gitignore
• Security headers configured
• Rate limiting on public endpoints

References

• .claude/supabase/references/RLS-POLICIES.md
• .claude/edge-functions/references/SECURITY.md
• plan/audit/ — Previous audit reports