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Secure API Access with WAF

Traefik Hub Feature

This middleware is available exclusively in Traefik Hub. Learn more about Traefik Hub's advanced features.

The Coraza Web Application Firewall middleware in Traefik Hub API Gateway provides comprehensive protection against common web application attacks. The middleware supports the Coraza rule syntax and is compatible with OWASP Core Rule Set (CRS), allowing you to leverage proven security rules maintained by the security community.

Basic WAF Protection

To protect your applications with custom security rules, apply the following configuration:

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: waf-protection
  namespace: apps
spec:
  plugin:
    coraza:
      directives:
        - SecRuleEngine On
        - SecRule REQUEST_URI "@streq /admin" "id:101,phase:1,t:lowercase,log,deny"
        - SecRule ARGS "@detectSQLi" "id:102,phase:2,block,msg:'SQL Injection Attack Detected',logdata:'Matched Data: %{MATCHED_VAR} found within %{MATCHED_VAR_NAME}'"

This configuration implements three security directives that work together to protect an application:

  • SecRuleEngine On: Activates the WAF engine to begin processing incoming requests. Without this directive, all other rules remain inactive regardless of their configuration.

  • Admin Path Protection: The second rule blocks all access to /admin paths by examining the request URI. This completely prevents access to administrative interfaces that often contain sensitive functionality like user management, system configuration, or database administration tools. The rule triggers during phase 1 (request headers processing) and applies lowercase transformation to catch variations like /Admin or /ADMIN.

  • SQL Injection Detection: The third rule scans request parameters (query strings and form data) for SQL injection patterns using Coraza's built-in detection engine. The ARGS variable covers query string parameters like ?id=1 and form data from POST requests like username=admin&password=123, but does not include cookies. SQL injection attacks attempt to manipulate database queries by injecting malicious SQL code through user inputs. When detected, the rule blocks the request and logs detailed information about the attempted attack, including which parameter contained the malicious payload.

apiVersion: traefik.io/v1alpha1
kind: IngressRoute
metadata:
  name: protected-app
  namespace: apps
spec:
  entryPoints:
    - websecure
  routes:
  - match: Path(`/my-app`)
    kind: Rule
    services:
    - name: whoami
      port: 80
    middlewares:
    - name: waf-protection
kind: Deployment
apiVersion: apps/v1
metadata:
  name: whoami
  namespace: apps
spec:
  replicas: 3
  selector:
    matchLabels:
      app: whoami
  template:
    metadata:
      labels:
        app: whoami
    spec:
      containers:
      - name: whoami
        image: traefik/whoami

---
apiVersion: v1
kind: Service
metadata:
  name: whoami
  namespace: apps
spec:
  ports:
  - port: 80
    name: whoami
  selector:
    app: whoami

Advanced Protection with OWASP Core Rule Set

To implement comprehensive protection using the OWASP Core Rule Set, which provides battle-tested rules against common attack patterns, apply the following configuration:

apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
  name: waf-crs-protection
  namespace: apps
spec:
  plugin:
    coraza:
      crsEnabled: true
      directives:
        - SecRuleEngine On
        - SecDefaultAction "phase:1,log,auditlog,deny,status:403"
        - SecDefaultAction "phase:2,log,auditlog,deny,status:403"
        - SecAction "id:900110, phase:1, pass, t:none, nolog, setvar:tx.inbound_anomaly_score_threshold=5, setvar:tx.outbound_anomaly_score_threshold=4"
        - SecAction "id:900200, phase:1, pass, t:none, nolog, setvar:'tx.allowed_methods=GET POST'"
        - Include @owasp_crs/REQUEST-911-METHOD-ENFORCEMENT.conf
        - Include @owasp_crs/REQUEST-949-BLOCKING-EVALUATION.conf

This advanced configuration implements OWASP Core Rule Set (CRS) protection with anomaly scoring:

  • SecDefaultAction for Phase 1 & 2: Sets default behavior for request processing phases. Phase 1 processes request headers while Phase 2 processes request body. When rules match, they log the event to both standard and audit logs, then deny the request with a 403 status code.

  • Anomaly Score Configuration: The first SecAction sets anomaly score thresholds where inbound_anomaly_score_threshold=5 means requests scoring 5 or higher are blocked, and outbound_anomaly_score_threshold=4 applies the same logic to responses. This scoring system allows multiple suspicious patterns to accumulate points rather than blocking on first detection, reducing false positives while maintaining security.

  • Allowed Methods Configuration: The second SecAction restricts HTTP methods to only GET and POST requests. This prevents potentially dangerous methods like PUT, DELETE, PATCH, or OPTIONS that could modify server resources or reveal system information.

  • METHOD-ENFORCEMENT Rule Set: The REQUEST-911-METHOD-ENFORCEMENT.conf file enforces the allowed HTTP methods policy defined above. It checks incoming requests against the permitted methods and contributes to the anomaly score for disallowed methods.

  • BLOCKING-EVALUATION Rule Set: The REQUEST-949-BLOCKING-EVALUATION.conf file evaluates the accumulated anomaly score against the configured thresholds. If the total score exceeds the threshold, it triggers the blocking action, preventing the request from reaching your application.

apiVersion: traefik.io/v1alpha1
kind: IngressRoute
metadata:
  name: crs-protected-app
  namespace: apps
spec:
  entryPoints:
    - websecure
  routes:
  - match: Path(`/my-app`)
    kind: Rule
    services:
    - name: whoami
      port: 80
    middlewares:
    - name: waf-crs-protection
kind: Deployment
apiVersion: apps/v1
metadata:
  name: whoami
  namespace: apps
spec:
  replicas: 3
  selector:
    matchLabels:
      app: whoami
  template:
    metadata:
      labels:
        app: whoami
    spec:
      containers:
      - name: whoami
        image: traefik/whoami

---
apiVersion: v1
kind: Service
metadata:
  name: whoami
  namespace: apps
spec:
  ports:
  - port: 80
    name: whoami
  selector:
    app: whoami

Warning

Starting with Traefik Hub v3.11.0, Coraza requires read/write permissions to /tmp. This requirement stems from upstream changes in the Coraza engine.

Advanced Configuration

Advanced options and detailed rule configuration are described in the reference page.

The WAF middleware supports extensive customization through Coraza directives. You can create custom rules, tune detection thresholds, configure logging levels, and integrate with external threat intelligence feeds. For comprehensive rule writing guidance, consult the Coraza documentation and OWASP CRS documentation.

Using Traefik OSS in Production?

If you are using Traefik at work, consider adding enterprise-grade API gateway capabilities or commercial support for Traefik OSS.

Adding API Gateway capabilities to Traefik OSS is fast and seamless. There's no rip and replace and all configurations remain intact. See it in action via this short video.