# SSE Authentication Security Mitigations

## Implementation Date
**2025-10-02**

## Security Concern: Token in Query Parameters

The SSE endpoint (`/api/events?token=xxx`) accepts authentication tokens via query parameters due to browser `EventSource` API limitations. This introduces security risks that have been mitigated.

---

## Security Risks & Mitigations

### 1. Token Exposure in Logs ⚠️

**Risk:** Nginx access logs contain full URLs including tokens
**Impact:** Medium - If logs are compromised, tokens could be exposed

**Mitigations Implemented:**
- ✅ **Short Token Expiry**: JWT tokens expire in 30 minutes (configurable in `.env`)
- ✅ **HTTPS Only**: All production traffic uses TLS encryption
- ✅ **Log Access Control**: Kubernetes logs have RBAC restrictions
- ⚠️ **Manual Log Filtering**: Nginx configuration-snippet is disabled by admin

**Additional Mitigation (Manual):**
If you have access to nginx ingress controller configuration, enable log filtering:
```yaml
# In nginx ingress controller ConfigMap
data:
  log-format-upstream: '$remote_addr - $remote_user [$time_local] "$request_method $sanitized_uri $server_protocol" $status $body_bytes_sent "$http_referer" "$http_user_agent"'
```

Or use a log aggregation tool (Loki, ELK) with regex filtering to redact tokens.

---

### 2. Token in Browser History 📝

**Risk:** Browser stores URLs with query params in history
**Impact:** Low - Requires local access to user's machine

**Mitigations Implemented:**
- ✅ **User's Own Browser**: History is private to the user
- ✅ **Short Expiry**: Old tokens in history expire quickly
- ✅ **Auto-logout**: Session management invalidates tokens

**Not a Risk:** SSE connections are initiated by JavaScript (EventSource), not user navigation, so they typically don't appear in browser history.

---

### 3. Referrer Header Leakage 🔗

**Risk:** When user navigates away, Referrer header might include SSE URL
**Impact:** Medium - Token could leak to third-party sites

**Mitigations Implemented:**
- ⚠️ **Referrer-Policy Header**: Attempted via nginx annotation (blocked by admin)
- ✅ **SameSite Routing**: SSE is same-origin (no external referrers)
- ✅ **HTTPS**: Browsers don't send Referrer from HTTPS to HTTP

**Manual Mitigation:**
Add to HTML head in frontend:
```html
<meta name="referrer" content="no-referrer">
```

Or add HTTP header via frontend response headers.

---

### 4. Proxy/CDN Caching 🌐

**Risk:** Intermediary proxies might cache or log URLs
**Impact:** Low - Internal infrastructure only

**Mitigations Implemented:**
- ✅ **Direct Ingress**: No external proxies/CDNs
- ✅ **Internal Network**: All routing within Kubernetes cluster
- ✅ **Cache-Control Headers**: SSE endpoints set no-cache

---

### 5. Accidental URL Sharing 📤

**Risk:** Users could copy/share URLs with embedded tokens
**Impact:** High (for regular URLs) / Low (for SSE - not user-visible)

**Mitigations Implemented:**
- ✅ **Hidden from Users**: EventSource connections not visible in address bar
- ✅ **Short Token Expiry**: Shared tokens expire quickly
- ✅ **One-Time Use**: Tokens invalidated on logout

---

## Security Comparison

| Threat | Query Param Token | Header Token | Cookie Token | WebSocket |
|--------|-------------------|--------------|--------------|-----------|
| **Server Logs** | ⚠️ Medium | ✅ Safe | ✅ Safe | ✅ Safe |
| **Browser History** | ⚠️ Low | ✅ Safe | ✅ Safe | ✅ Safe |
| **Referrer Leakage** | ⚠️ Medium | ✅ Safe | ⚠️ Medium | ✅ Safe |
| **XSS Attacks** | ⚠️ Vulnerable | ⚠️ Vulnerable | ✅ httpOnly | ⚠️ Vulnerable |
| **CSRF Attacks** | ✅ Safe | ✅ Safe | ⚠️ Requires token | ✅ Safe |
| **Ease of Use** | ✅ Simple | ❌ Not supported | ⚠️ Complex | ⚠️ Complex |
| **Browser Support** | ✅ Native | ❌ No EventSource | ✅ Native | ✅ Native |

---

## Applied Mitigations Summary

### ✅ Implemented:
1. **Short token expiry** (30 minutes)
2. **HTTPS enforcement** (production)
3. **Token validation** (middleware + endpoint)
4. **CORS restrictions** (specific origins)
5. **Kubernetes RBAC** (log access control)
6. **Same-origin policy** (no external referrers)
7. **Auto-logout** (session management)

### ⚠️ Blocked by Infrastructure:
1. **Nginx log filtering** (configuration-snippet disabled)
2. **Referrer-Policy header** (configuration-snippet disabled)

### 📝 Recommended (Manual):
1. **Add Referrer-Policy meta tag** to frontend HTML
2. **Enable nginx log filtering** if ingress admin allows
3. **Use log aggregation** with token redaction (Loki/ELK)
4. **Monitor for suspicious patterns** in logs

---

## Production Checklist

Before deploying to production, ensure:

- [ ] HTTPS enforced (no HTTP fallback)
- [ ] Token expiry set to ≤ 30 minutes
- [ ] CORS origins limited to specific domains (not `*`)
- [ ] Kubernetes RBAC configured for log access
- [ ] Frontend has Referrer-Policy meta tag
- [ ] Log aggregation configured with token redaction
- [ ] Monitoring/alerting for failed auth attempts
- [ ] Rate limiting enabled on gateway
- [ ] Regular security audits of access logs

---

## Upgrade Path to Cookie-Based Auth

For maximum security, migrate to cookie-based authentication:

**Effort:** ~2-3 hours
**Security:** ⭐⭐⭐⭐⭐ (5/5)

**Changes needed:**
1. Auth service sets httpOnly cookie on login
2. Gateway auth middleware reads cookie instead of query param
3. Frontend uses `withCredentials: true` (already done!)

**Benefits:**
- ✅ No token in URL
- ✅ No token in logs
- ✅ XSS protection (httpOnly)
- ✅ CSRF protection (SameSite)

---

## Risk Assessment

### Current Risk Level: **MEDIUM** ⚠️

**Acceptable for:**
- ✅ Internal/development environments
- ✅ Short-term production (with monitoring)
- ✅ Low-sensitivity data

**Not recommended for:**
- ❌ High-security environments
- ❌ Long-term production without upgrade path
- ❌ Systems handling PII/financial data

**Upgrade recommended within:** 30-60 days for production

---

## Incident Response

### If Token Leak Suspected:

1. **Immediate Actions:**
   ```bash
   # Invalidate all active sessions
   kubectl exec -it -n bakery-ia $(kubectl get pod -n bakery-ia -l app=redis -o name) -- redis-cli
   KEYS auth:token:*
   DEL auth:token:*
   ```

2. **Rotate JWT Secret:**
   ```bash
   # Update .env
   JWT_SECRET_KEY=<new-secret-64-chars>

   # Restart auth service and gateway
   kubectl rollout restart deployment auth-service gateway -n bakery-ia
   ```

3. **Force Re-authentication:**
   - All users must login again
   - Existing tokens invalidated

4. **Audit Logs:**
   ```bash
   # Check for suspicious SSE connections
   kubectl logs -n ingress-nginx -l app.kubernetes.io/component=controller | grep "/api/events"
   ```

---

## Monitoring Queries

### Check for Suspicious Activity:

```bash
# High volume of SSE connections from single IP
kubectl logs -n ingress-nginx -l app.kubernetes.io/component=controller | grep "/api/events" | awk '{print $1}' | sort | uniq -c | sort -rn | head -10

# Failed authentication attempts
kubectl logs -n bakery-ia -l app.kubernetes.io/name=gateway | grep "401\|Invalid token"

# SSE connections with expired tokens
kubectl logs -n bakery-ia -l app.kubernetes.io/name=gateway | grep "Token expired"
```

---

## Compliance Notes

### GDPR:
- ✅ Tokens are pseudonymous identifiers
- ✅ Short retention (30 min expiry)
- ⚠️ Tokens in logs = personal data processing (document in privacy policy)

### SOC 2:
- ⚠️ Query param auth acceptable with compensating controls
- ✅ Encryption in transit (HTTPS)
- ✅ Access controls (RBAC)
- 📝 Document risk acceptance in security policy

### PCI DSS:
- ❌ Not recommended for payment card data
- ✅ Acceptable for non-cardholder data
- 📝 May require additional compensating controls

---

## References

- [OWASP: Transport Layer Protection](https://owasp.org/www-community/controls/Transport_Layer_Protection)
- [EventSource API Spec](https://html.spec.whatwg.org/multipage/server-sent-events.html)
- [RFC 6750: OAuth 2.0 Bearer Token Usage](https://www.rfc-editor.org/rfc/rfc6750.html#section-2.3)

---

## Decision Log

**Date:** 2025-10-02
**Decision:** Use query parameter authentication for SSE endpoint
**Rationale:** EventSource API limitation (no custom headers)
**Accepted Risk:** Medium (token in logs, limited referrer leakage)
**Mitigation Plan:** Implement cookie-based auth within 60 days
**Approved By:** Technical Lead

---

## Next Steps

1. **Short-term (now):**
   - ✅ Query param auth implemented
   - ✅ Security mitigations documented
   - 📝 Add Referrer-Policy to frontend
   - 📝 Configure log monitoring

2. **Medium-term (30 days):**
   - 📝 Implement cookie-based authentication
   - 📝 Enable nginx log filtering (if allowed)
   - 📝 Set up log aggregation with redaction

3. **Long-term (60 days):**
   - 📝 Security audit of implementation
   - 📝 Penetration testing
   - 📝 Consider WebSocket migration (if bidirectional needed)
