Minimize the admission of containers wishing to share the host network namespace (PSP)

Do not generally permit containers to be run with the hostNetwork flag set to true. A container running in the host's network namespace could access the local loopback device, and could access network traffic to and from other pods. There should be at least one CloudGuard Admission Control (CAC) rule or PodSecurityPolicy (PSP) defined which does not permit containers to share the host network namespace. If you have need to run containers which require hostNetwork, this should be defined in a separate CAC rule or PSP and you should carefully check RBAC controls to ensure that only limited service accounts and users are given permission to access that CAC rule or PSP.

Risk Level: High
Cloud Entity: Pod Security Policies
CloudGuard Rule ID: D9.K8S.IAM.22
Covered by Spectral: Yes
Category: Security, Identity, & Compliance

GSL LOGIC

List<KubernetesPodSecurityPolicy> where items length() > 0 should have items contain [spec.hostNetwork != 'true']

REMEDIATION

Create a PSP as described in the Kubernetes documentation, ensuring that the .spec.hostNetwork field is omitted or set to false.

References

  1. https://kubernetes.io/docs/concepts/policy/pod-security-policy

Pod Security Policies

A Pod Security Policy is a cluster-level resource that controls security sensitive aspects of the pod specification. The PodSecurityPolicy objects define a set of conditions that a pod must run with in order to be accepted into the system, as well as defaults for the related fields.

Compliance Frameworks

  • CIS Amazon Elastic Kubernetes Service (EKS) Benchmark v1.0.1
  • CIS Amazon Elastic Kubernetes Service (EKS) Benchmark v1.1.0
  • CIS Amazon Elastic Kubernetes Service (EKS) Benchmark v1.2.0
  • CIS Amazon Elastic Kubernetes Service (EKS) Benchmark v1.3.0
  • CIS Google Kubernetes Engine (GKE) Benchmark v1.2.0
  • CIS Google Kubernetes Engine (GKE) Benchmark v1.4.0
  • CIS Kubernetes Benchmark v1.20
  • CIS Kubernetes Benchmark v1.23
  • CIS Kubernetes Benchmark v1.5.1
  • CIS Kubernetes Benchmark v1.6.1
  • CIS Microsoft Kubernetes Engine (AKS) Benchmark v1.1.0
  • CIS Microsoft Kubernetes Engine (AKS) Benchmark v1.3.0
  • Kubernetes NIST.SP.800-190
  • Kubernetes v.1.13 CloudGuard Best Practices
  • Kubernetes v.1.14 CloudGuard Best Practices