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Excessive Privileges - Kubernetes

Description​

Kubernetes default configuration is overly permissive, allowing users to escalate privileges or execute commands as privileged users.

Impact​

Gain total control over one or more PoDs.

Recommendation​

Set strict security policy disabling potentially harmful actions and restricting the user permissions.

Threat​

Authenticated attacker with local access to PoD or container.

Expected Remediation Time​

⌚ 30 minutes.

Score​

Default score using CVSS 3.1. It may change depending on the context of the vulnerability.

Base​

  • Attack vector: L
  • Attack complexity: L
  • Privileges required: L
  • User interaction: N
  • Scope: U
  • Confidentiality: L
  • Integrity: L
  • Availability: L

Temporal​

  • Exploit code madurity: U
  • Remediation level: O
  • Report confidence: C

Result​

  • Vector string: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C
  • Score:
    • Base: 5.3
    • Temporal: 4.6
  • Severity:
    • Base: Medium
    • Temporal: Medium

Code Examples​

Compliant code​

The resource has enabled safe security policies by restricting privileges to authorized users

apiVersion: v1
kind: Pod
metadata:
  name: rss-site
  labels:
    app: web
spec:
  privileged: false
  containers:
    - name: front-end
      image: nginx
      ports:
        - containerPort: 80
      securityContext:
        capabilities:
            add:
              - SYS_ADMIN
              - NET_ADMIN
    - name: rss-reader
      image: nickchase/rss-php-nginxv1
      ports:
        - containerPort: 88
apiVersion: v1
kind: Pod
metadata:
  name: rss-site
  labels:
    app: web
spec:
  containers:
    - name: front-end
      image: nginx
      ports:
        - containerPort: 80
      securityContext:
        allowPrivilegeEscalation: false
        capabilities:
          drop:
            - all
          add:
            - NET_BIND_SERVICE
    - name: rss-reader
      image: nickchase/rss-php-nginxv1
      ports:
        - containerPort: 88

Non compliant code​

The resource does not enable safe security policies allowing privileged execution

apiVersion: v1
kind: Pod
metadata:
  name: rss-site
  labels:
    app: web
spec:
  privileged: true
  containers:
    - name: front-end
      image: nginx
      ports:
        - containerPort: 80
      securityContext:
        capabilities:
            add:
              - SYS_ADMIN
              - NET_ADMIN
    - name: rss-reader
      image: nickchase/rss-php-nginxv1
      ports:
        - containerPort: 88
apiVersion: v1
kind: Pod
metadata:
  name: rss-site
  labels:
    app: web
spec:
  containers:
    - name: front-end
      image: nginx
      ports:
        - containerPort: 80
      securityContext:
        allowPrivilegeEscalation: true
        capabilities:
          drop:
            - all
          add:
            - NET_BIND_SERVICE
    - name: rss-reader
      image: nickchase/rss-php-nginxv1
      ports:
        - containerPort: 88

Details​

https://kubernetes.io/docs/concepts/security/pod-security-standards/#restricted https://kubernetes.io/docs/concepts/policy/pod-security-policy/

Requirements​

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