CIS Kubernetes Benchmark

This document introduces the CIS Kubernetes Benchmark, explains how to audit your compliance with the benchmark, and explains what Google Distributed Cloud (GDC) air-gapped configures when you cannot implement a recommendation yourself.

About the CIS benchmarks

The Center for Internet Security (CIS) releases benchmarks for best practice security recommendations. The CIS Kubernetes Benchmark provides a set of recommendations for configuring Kubernetes to support a strong security posture. The Benchmark is tied to a specific Kubernetes release. The CIS Kubernetes Benchmark is written for the open source Kubernetes distribution and intended to be as universally applicable across distributions as possible.

Access the benchmark

The CIS Kubernetes Benchmark is available on the CIS website.

Recommendation levels

The following table describes the recommendation levels in the CIS Kubernetes Benchmark.

Level Description
Level 1

Recommendations exhibit one or more of the following characteristics:

  • Be practical and prudent.
  • Provide a clear security benefit.
  • Don't inhibit the utility of the technology beyond acceptable means.

    		•
    Level 2

    Extends the Level 1 profile.

    Recommendations exhibit one or more of the following characteristics:

  • Apply to environments or use cases where security is paramount.
  • Acts as defense in depth measure.
  • Might negatively inhibit the utility or performance of the technology.

    		•

    Assessment status

    An assessment status is included for every recommendation. The assessment status indicates whether the given recommendation can be automated or requires manual steps to implement. Both statuses are equally important and are determined and supported as defined in the following tables.

    Versions

    The assessment refers to the following versions:

    GDC on bare metal version Kubernetes version CIS Kubernetes Benchmark version
    1.30 1.30.9 v0.10.4

    Status of GDC air-gapped Kubernetes cluster

    # Recommendation Level Status
    1 Control Plane Security Configuration
    1.1 Control Plane Node Configuration Files
    1.1.1 Ensure that the API server pod specification file permissions are set to 600 or more restrictive (Automated) L1 Pass
    1.1.2 Ensure that the API server pod specification file ownership is set to root:root (Automated) L1 Pass
    1.1.3 Ensure that the controller manager pod specification file permissions are set to 600 or more restrictive (Automated) L1 Pass
    1.1.4 Ensure that the controller manager pod specification file ownership is set to root:root (Automated) L1 Pass
    1.1.5 Ensure that the scheduler pod specification file permissions are set to 600 or more restrictive (Automated) L1 Pass
    1.1.6 Ensure that the scheduler pod specification file ownership is set to root:root (Automated) L1 Pass
    1.1.7 Ensure that the etcd pod specification file permissions are set to 600 or more restrictive (Automated) L1 Pass
    1.1.8 Ensure that the etcd pod specification file ownership is set to root:root (Automated) L1 Pass
    1.1.9 Ensure that the Container Network Interface file permissions are set to 600 or more restrictive (Manual) L1 Warn
    1.1.10 Ensure that the Container Network Interface file ownership is set to root:root (Manual) L1 Warn
    1.1.11 Ensure that the etcd data directory permissions are set to 700 or more restrictive (Automated) L1 Pass
    1.1.12 Ensure that the etcd data directory ownership is set to etcd:etcd (Automated) L1 Fail
    1.1.13 Ensure that the default administrative credential file permissions are set to 600 (Automated) L1 Pass
    1.1.14 Ensure that the default administrative credential file ownership is set to root:root (Automated) L1 Pass
    1.1.15 Ensure that the scheduler.conf file permissions are set to 600 or more restrictive (Automated) L1 Pass
    1.1.16 Ensure that the scheduler.conf file ownership is set to root:root (Automated) L1 Fail
    1.1.17 Ensure that the controller-manager.conf file permissions are set to 600 or more restrictive (Automated) L1 Pass
    1.1.18 Ensure that the controller-manager.conf file ownership is set to root:root (Automated) L1 Fail
    1.1.19 Ensure that the Kubernetes PKI directory and file ownership is set to root:root (Automated) L1 Fail
    1.1.20 Ensure that the Kubernetes PKI certificate file permissions are set to 600 or more restrictive (Manual) L1 Warn
    1.1.21 Ensure that the Kubernetes PKI key file permissions are set to 600 (Manual) L1 Warn
    1.2 API Server
    1.2.1 Ensure that the --anonymous-auth argument is set to false (Manual) L1 Warn
    1.2.2 Ensure that the --token-auth-file parameter is not set (Automated) L1 Pass
    1.2.3 Ensure that the --DenyServiceExternalIPs is set (Manual) L1 Warn
    1.2.4 Ensure that the --kubelet-client-certificate and --kubelet-client-key arguments are set as appropriate (Automated) L1 Pass
    1.2.5 Ensure that the --kubelet-certificate-authority argument is set as appropriate (Automated) L1 Pass
    1.2.6 Ensure that the --authorization-mode argument is not set to AlwaysAllow (Automated) L1 Pass
    1.2.7 Ensure that the --authorization-mode argument includes Node (Automated) L1 Pass
    1.2.8 Ensure that the --authorization-mode argument includes RBAC (Automated) L1 Pass
    1.2.9 Ensure that the admission control plugin EventRateLimit is set (Manual) L1 Warn
    1.2.10 Ensure that the admission control plugin AlwaysAdmit is not set (Automated) L1 Pass
    1.2.11 Ensure that the admission control plugin AlwaysPullImages is set (Manual) L1 Warn
    1.2.12 Ensure that the admission control plugin ServiceAccount is set (Automated) L1 Pass
    1.2.13 Ensure that the admission control plugin NamespaceLifecycle is set (Automated) L1 Pass
    1.2.14 Ensure that the admission control plugin NodeRestriction is set (Automated) L1 Pass
    1.2.15 Ensure that the --profiling argument is set to false (Automated) L1 Pass
    1.2.16 Ensure that the --audit-log-path argument is set (Automated) L1 Pass
    1.2.17 Ensure that the --audit-log-maxage argument is set to 30 or as appropriate (Automated) L1 Pass
    1.2.18 Ensure that the --audit-log-maxbackup argument is set to 10 or as appropriate (Automated) L1 Pass
    1.2.19 Ensure that the --audit-log-maxsize argument is set to 100 or as appropriate (Automated) L1 Pass
    1.2.20 Ensure that the --request-timeout argument is set as appropriate (Manual) L1 Warn
    1.2.21 Ensure that the --service-account-lookup argument is set to true (Automated) L1 Pass
    1.2.22 Ensure that the --service-account-key-file argument is set as appropriate (Automated) L1 Pass
    1.2.23 Ensure that the --etcd-certfile and --etcd-keyfile arguments are set as appropriate (Automated) L1 Pass
    1.2.24 Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate (Automated) L1 Pass
    1.2.25 Ensure that the --client-ca-file argument is set as appropriate (Automated) L1 Pass
    1.2.26 Ensure that the --etcd-cafile argument is set as appropriate (Automated) L1 Pass
    1.2.27 Ensure that the --encryption-provider-config argument is set as appropriate (Manual) L1 Pass
    1.2.28 Ensure that encryption providers are appropriately configured (Manual) L1 Pass
    1.2.29 Ensure that the API Server only makes use of Strong Cryptographic Ciphers (Manual) L1 Pass
    1.3 Controller Manager
    1.3.1 Ensure that the --terminated-pod-gc-threshold argument is set as appropriate (Manual) L1 Pass
    1.3.2 Ensure that the --profiling argument is set to false (Automated) L1 Pass
    1.3.3 Ensure that the --use-service-account-credentials argument is set to true (Automated) L1 Pass
    1.3.4 Ensure that the --service-account-private-key-file argument is set as appropriate (Automated) L1 Pass
    1.3.5 Ensure that the --root-ca-file argument is set as appropriate (Automated) L1 Pass
    1.3.6 Ensure that the RotateKubeletServerCertificate argument is set to true (Automated) L2 Pass
    1.3.7 Ensure that the --bind-address argument is set to 127.0.0.1 (Automated) L1 Fail
    1.4 Scheduler
    1.4.1 Ensure that the --profiling argument is set to false (Automated) L1 Pass
    1.4.2 Ensure that the --bind-address argument is set to 127.0.0.1 (Automated) L1 Fail

    Audit benchmarks

    Specific instructions for auditing each recommendation is available as part of the relevant CIS Benchmark. However, you might want to automate some of these checks to simplify the verification of these controls in your environment. The following tool can help with this.

    Automated auditing of the CIS Kubernetes Benchmark

    You can use an open-source tool kube-bench to test your cluster configuration against the CIS Kubernetes Benchmark.

    Make sure to specify the appropriate version. For example:

    kube-bench --benchmark BENCHMARK_VERSION

    Replace BENCHMARK_VERSION with the CIS Kubernetes Benchmark version you're using to assess your cluster.

    To run specific CIS Benchmark sections, such as master, node, or etcd, use the run --targets command. For example:

    kube-bench run --targets master,node

    For more information, see kube-bench documentation on running kube-bench and commands and flags.