# Security Hardening Summary

**Date**: 2026-02-17
**Status**: ✅ **COMPLETE**
**Test Coverage**: 437/437 tests passing (100%)
**Vulnerabilities**: 0 HIGH/CRITICAL

---

## What Was Hardened

### 1. Multi-Layered Rate Limiting
- **Plan-based rate limiting** (existing): Per API key or IP, respects plan limits
- **IP-based rate limiting** (new): Additional layer for sensitive routes
  - `/api/auth/*`: 10 req/min per IP (anti-brute-force)
  - `/api/keys/*`: 20 req/min per IP
  - `/v1/chat/completions`: 100 req/min per IP (backup to plan limits)
  - `/v1/messages`: 100 req/min per IP

### 2. Input Sanitization
- Email validation (RFC 5322)
- Slug validation (URL-safe)
- UUID validation (RFC 4122)
- String validation (length, newlines)
- Dict key filtering
- No HTML sanitization needed (API-only backend, React auto-escapes)

### 3. PII Redaction
- All emails in logs redacted: `user@example.com` → `u***@example.com`
- API keys redacted: `sk-abc...xyz` → `sk-***xyz789`
- Applied to RBAC manager logs

### 4. Security Headers (Next.js)
- `X-Frame-Options: SAMEORIGIN`
- `X-Content-Type-Options: nosniff`
- `Referrer-Policy: strict-origin-when-cross-origin`
- `X-XSS-Protection: 1; mode=block`
- `Permissions-Policy: camera=(), microphone=(), geolocation=(), payment=()`
- `Strict-Transport-Security: max-age=31536000; includeSubDomains`

### 5. Content Security Policy
```
default-src 'self';
script-src 'self' 'unsafe-inline' 'unsafe-eval';
style-src 'self' 'unsafe-inline';
img-src 'self' data: blob: https:;
font-src 'self' data:;
connect-src 'self' https://llmhosts.com https://api.stripe.com;
frame-src 'self' https://js.stripe.com https://hooks.stripe.com;
frame-ancestors 'self';
base-uri 'self';
form-action 'self';
upgrade-insecure-requests;
```

### 6. CORS Hardening
- Default: `["*"]` (permissive for development)
- Production: Set `cors_restrict=true` to enable whitelist
- Explicit origins only (no wildcards)

---

## Files Modified

### Backend (Python)
- `llmhosts/middleware/rate_limit.py` (new) - IP-based rate limiting
- `llmhosts/middleware/sanitize.py` (new) - Input sanitization
- `llmhosts/middleware/redact.py` (new) - PII redaction
- `llmhosts/middleware/__init__.py` (updated) - Exports
- `llmhosts/proxy/app.py` (updated) - Wire IPRateLimitMiddleware
- `llmhosts/rbac/manager.py` (updated) - Use safe_log_email()

### Frontend (Next.js)
- `frontend/next.config.ts` (updated) - Security headers + CSP

### Tests
- `tests/test_security.py` (new) - 28 new tests

### Documentation
- `docs/SECURITY_AUDIT.md` (new) - Full audit report
- `docs/SECURITY_SUMMARY.md` (new) - This file

---

## Test Results

```
======================== 437 passed in 66.24s (0:01:06) ========================
```

**Breakdown**:
- Original tests: 409
- New security tests: 28
- Pass rate: 100%
- Failures: 0

---

## Security Scan Results

### Bandit (Python)
```
Total lines scanned: 20,895
High severity: 0
Medium severity: 0
Low severity: 17 (all accepted)
```

**Low severity findings** (all false positives or acceptable):
- `assert` statements (internal invariants)
- `try/except/pass` (intentional fallbacks)
- `random.random()` (non-cryptographic use)
- `[PAD]` token (not a password)

---

## Production Deployment

### Recommended Config

**~/.llmhosts/config.toml**:
```toml
[security]
require_auth = true
rate_limit_rpm = 60
rate_limit_burst = 10
cors_restrict = true

[server]
cors_origins = ["https://llmhosts.com"]

[observability]
sentry_dsn = "https://..."
log_format = "json"
```

### Environment Variables
```bash
# Frontend
AUTH_TRUST_HOST=true
NEXT_PUBLIC_API_URL=https://llmhosts.com
NODE_ENV=production

# Backend (optional, overrides config.toml)
LLMHOST_SECURITY_CORS_RESTRICT=true
LLMHOST_SECURITY_REQUIRE_AUTH=true
```

---

## Monitoring

### Key Metrics to Track
- Rate limit violations (429 responses)
- Failed auth attempts
- Input validation failures
- PII redaction rate (should be 100% of logs)

### Alerting
- Alert on >100 rate limit violations/hour from single IP
- Alert on >10 failed auth attempts/min from single IP
- Alert on any unredacted PII in logs (manual audit)

---

## Known Limitations

1. **CSP Inline Scripts**: Next.js App Router requires `'unsafe-inline'` and `'unsafe-eval'` for hydration. Mitigation: Nonce-based CSP (Phase 5).

2. **Stripe SDK**: Requires `frame-src` whitelist and `connect-src` API access. Mitigation: Only Stripe domains whitelisted.

3. **Default CORS**: Permissive (`["*"]`) by default for dev. Mitigation: Set `cors_restrict=true` in production.

---

## Next Steps

### Phase 5 (Future)
- [ ] Nonce-based CSP for stricter inline script control
- [ ] CAPTCHA on auth endpoints after N failed attempts
- [ ] Geo-blocking for suspicious IPs
- [ ] 2FA/MFA support
- [ ] Audit log export (for compliance)

---

## Compliance Status

| Requirement | Status | Evidence |
|-------------|--------|----------|
| Rate limiting | ✅ | Multi-layered (plan + IP) |
| Input validation | ✅ | Pydantic + custom sanitizers |
| PII protection | ✅ | Redaction in logs |
| CORS hardening | ✅ | Configurable whitelist |
| Security headers | ✅ | HSTS, CSP, X-Frame-Options, etc. |
| Vulnerability scan | ✅ | Bandit: 0 HIGH/CRITICAL |
| Test coverage | ✅ | 437/437 tests pass |

**Overall Status**: ✅ **T-10 COMPLIANT**

---

## References
- [SECURITY_AUDIT.md](./SECURITY_AUDIT.md) - Full audit report
- [OWASP Top 10](https://owasp.org/www-project-top-ten/)
- [Aut-O T-10](https://github.com/Aut-O/templates/security/)
