Guides

Minimize the admission of containers with added capabilities (PSP)

Do not generally permit containers with capabilities assigned beyond the default set. Containers run with a default set of capabilities as assigned by the Container Runtime. Capabilities outside this set can be added to containers which could expose them to risks of container breakout attacks. There should be at least one PodSecurityPolicy (PSP) defined which prevents containers with capabilities beyond the default set from launching. If you need to run containers with additional capabilities, this should be defined in a separate PSP and you should carefully check RBAC controls to ensure that only limited service accounts and users are given permission to access that PSP.

Suggest Edits

Risk Level: High
Cloud Entity: Pod Security Policies
CloudGuard Rule ID: D9.K8S.IAM.38
Covered by Spectral: Yes
Category: Security, Identity, & Compliance

GSL LOGIC

List<KubernetesPodSecurityPolicy> where items length() > 0  should have items contain [(not spec.allowedCapabilities) or (spec.allowedCapabilities contain [isEmpty()])]

REMEDIATION

Ensure that allowedCapabilities is not present in PSPs for the cluster unless it is set to an empty array.

References

  1. https://kubernetes.io/docs/concepts/policy/pod-security-policy/#enabling-pod-security-policies
  2. https://www.nccgroup.com/globalassets/our-research/us/whitepapers/2016/june/container_whitepaper.pdf (EKS)

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 v.1.14 CloudGuard Best Practices

Updated over 1 year ago