This document explains what the CIS Kubernetes and Google Kubernetes Engine (GKE) Benchmarks are, how to audit your compliance with the Benchmarks, and what GKE configures where you cannot directly audit or implement a recommendation yourself.
Using the CIS Benchmarks
The Center for Internet Security (CIS) releases benchmarks for best practice security recommendations. The CIS Kubernetes Benchmark is 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.
With a managed service like GKE, not all items on the Benchmark are your responsibility, and there are recommendations that you cannot audit or remediate directly yourself. If you are running on GKE, use the CIS GKE Benchmark, which is a child benchmark of the CIS Kubernetes Benchmark, meant specifically to be applied to the GKE distribution. This draws from the existing CIS Benchmark, but removes items that are not configurable or managed by the user and adds additional controls that are Google Cloud-specific.
Multiple set of Benchmarks
With GKE, you can use CIS Benchmarks for GKE, Kubernetes, Docker, Container-Optimized OS, and Linux. To download up-to-date benchmarks for these products, visit the CIS Benchmark website.
The default container runtime, containerd, does not have a CIS Benchmark.
The Windows Server nodes used with GKE are not scored against an appropriate CIS benchmark because Windows Server CIS benchmarks do not specifically allow for Kubernetes usage, and the Kubernetes CIS benchmarks do not currently accommodate Windows nodes.
Some tools attempt to analyze Kubernetes nodes against multiple CIS Benchmarks (e.g. Linux, Docker, and Kubernetes) and combine the results. This often results in confusing and potentially contradictory advice because those benchmarks weren't designed to be combined and applied in a Kubernetes environment.
Shared responsibility model
In GKE, under the Shared responsibility model, Google manages the following Kubernetes components:
- The control plane, including the control plane VMs, API server, other components on the VMs, and etcd.
- The Kubernetes distribution.
- The nodes' operating system.
Configurations related to these items are generally not available for you to audit or modify in GKE.
You are still responsible for upgrading the nodes that run your workloads, and the workloads themselves. You can generally audit and remediate any recommendations to these components.
Ability to audit and remediate
The CIS GKE Benchmark draws from the existing CIS Kubernetes Benchmark, but remove items that are not configurable or managed by the user, and add additional controls that are Google Cloud-specific.
The sections of the CIS GKE Benchmark are:
- Control Plane Components, etcd, and Control Plane Configuration (sections 1, 2 and 3) are from the CIS Kubernetes Benchmark. These generally cannot be audited or remediated on GKE.
- Worker Nodes (section 4) is from the CIS Kubernetes Benchmark. Some of these items can be audited or remediated on GKE, but instructions may be different.
- Policies (section 5) is also from the CIS Kubernetes Benchmark. These are generally directly applicable to GKE, without any change in instructions.
- Managed services (section 6) in the CIS GKE Benchmark is net new content for GKE specifically. This section contains all of the recommendations that are specific to Google Cloud controls. These can be audited and remediated on GKE.
For the items that cannot be audited or remediated on GKE, see the section on Default values to understand how a default cluster created in GKE performs against the CIS Kubernetes Benchmark.
Versions
Note that the version numbers for different Benchmarks may not be the same.
This document refers to these versions:
| Kubernetes version | CIS Kubernetes Benchmark version | CIS GKE Benchmark version |
|---|---|---|
| 1.15 | 1.5.0 | 1.0.0 |
CIS Kubernetes Benchmark
Accessing the Benchmark
The CIS Kubernetes Benchmark is available on the CIS website.
Recommendation levels
In the CIS Kubernetes Benchmark:
| Level | Description |
|---|---|
| Level 1 | Recommendations intend to: |
| Level 2 | Extends the Level 1 profile. Recommendations exhibit one or more of the following characteristics: |
Recommendation scoring
In the CIS Kubernetes Benchmark:
| Scoring | Description |
|---|---|
| Scored | Failure to comply with these recommendations will decrease the final benchmark score. |
| Not Scored | Failure to comply with these recommendations will not decrease the final benchmark score. |
Evaluation on GKE
We use the following values to specify the status of Kubernetes recommendations in GKE:
| Status | Description |
|---|---|
| Pass | Complies with a Benchmark recommendation. |
| Fail | Does not comply with a Benchmark recommendation. |
| Equivalent Control | Does not comply with the exact terms in the Benchmark recommendation, but other mechanisms in GKE exist to provide equivalent security controls. |
| Depends on Environment | GKE does not configure items related to this recommendation. The user's configuration determines whether their environment complies with a Benchmark recommendation. |
Status on GKE
When creating a new GKE cluster with the specified version, here's how it will perform against the CIS Kubernetes Benchmark.
Status of default GKE cluster:
| # | Recommendation | Scored/ Not Scored | Level | Default Status |
|---|---|---|---|---|
| 1 | Control Plane Components | |||
| 1.1 | Control Plane Node Configuration Files | |||
| 1.1.1 | Ensure that the API server pod specification file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 1.1.2 | Ensure that the API server pod specification file ownership is set to root:root |
Scored | L1 | Pass |
| 1.1.3 | Ensure that the controller manager pod specification file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 1.1.4 | Ensure that the controller manager pod specification file ownership is set to root:root |
Scored | L1 | Pass |
| 1.1.5 | Ensure that the scheduler pod specification file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 1.1.6 | Ensure that the scheduler pod specification file ownership is set to root:root |
Scored | L1 | Pass |
| 1.1.7 | Ensure that the etcd pod specification file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 1.1.8 | Ensure that the etcd pod specification file ownership is set to root:root |
Scored | L1 | Pass |
| 1.1.9 | Ensure that the Container Network Interface file permissions are set to 644 or more restrictive |
Not Scored | L1 | Pass |
| 1.1.10 | Ensure that the Container Network Interface file ownership is set to root:root |
Not Scored | L1 | Pass |
| 1.1.11 | Ensure that the etcd data directory permissions are set to 700 or more restrictive |
Scored | L1 | Pass |
| 1.1.12 | Ensure that the etcd data directory ownership is set to etcd:etcd |
Scored | L1 | Pass |
| 1.1.13 | Ensure that the admin.conf file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 1.1.14 | Ensure that the admin.conf file ownership is set to root:root |
Scored | L1 | Pass |
| 1.1.15 | Ensure that the scheduler.conf file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 1.1.16 | Ensure that the scheduler.conf file ownership is set to root:root |
Scored | L1 | Pass |
| 1.1.17 | Ensure that the controller-manager.conf file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 1.1.18 | Ensure that the controller-manager.conf file ownership is set to root:root |
Scored | L1 | Pass |
| 1.1.19 | Ensure that the Kubernetes PKI directory and file ownership is set to root:root |
Scored | L1 | Pass |
| 1.1.20 | Ensure that the Kubernetes PKI certificate file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 1.1.21 | Ensure that the Kubernetes PKI key file permissions are set to 600 |
Scored | L1 | Pass |
| 1.2 | API Server | |||
| 1.2.1 | Ensure that the --anonymous-auth argument is set to false | Not Scored | L1 | Fail |
| 1.2.2 | Ensure that the --basic-auth-file argument is not set | Scored | L1 | Pass |
| 1.2.3 | Ensure that the --token-auth-file parameter is not set | Scored | L1 | Fail |
| 1.2.4 | Ensure that the --kubelet-https argument is set to true | Scored | L1 | Pass |
| 1.2.5 | Ensure that the --kubelet-client-certificate and --kubelet-client-key arguments are set as appropriate | Scored | L1 | Pass |
| 1.2.6 | Ensure that the --kubelet-certificate-authority argument is set as appropriate | Scored | L1 | Pass |
| 1.2.7 | Ensure that the --authorization-mode argument is not set to AlwaysAllow | Scored | L1 | Pass |
| 1.2.8 | Ensure that the --authorization-mode argument includes Node | Scored | L1 | Pass |
| 1.2.9 | Ensure that the --authorization-mode argument includes RBAC | Scored | L1 | Pass |
| 1.2.10 | Ensure that the admission control plugin EventRateLimit is set | Not Scored | L1 | Fail |
| 1.2.11 | Ensure that the admission control plugin AlwaysAdmit is not set | Scored | L1 | Pass |
| 1.2.12 | Ensure that the admission control plugin AlwaysPullImages is set | Not Scored | L1 | Fail |
| 1.2.13 | Ensure that the admission control plugin SecurityContextDeny is set if PodSecurityPolicy is not used | Not Scored | L1 | Fail |
| 1.2.14 | Ensure that the admission control plugin ServiceAccount is set | Scored | L1 | Pass |
| 1.2.15 | Ensure that the admission control plugin NamespaceLifecycle is set | Scored | L1 | Pass |
| 1.2.16 | Ensure that the admission control plugin PodSecurityPolicy is set | Scored | L1 | Fail |
| 1.2.17 | Ensure that the admission control plugin NodeRestriction is set | Scored | L1 | Pass |
| 1.2.18 | Ensure that the --insecure-bind-address argument is not set | Scored | L1 | Pass |
| 1.2.19 | Ensure that the --insecure-port argument is set to 0 | Scored | L1 | Pass |
| 1.2.20 | Ensure that the --secure-port argument is not set to 0 | Scored | L1 | Pass |
| 1.2.21 | Ensure that the --profiling argument is set to false | Scored | L1 | Fail |
| 1.2.22 | Ensure that the --audit-log-path argument is set | Scored | L1 | Equivalent Control |
| 1.2.23 | Ensure that the --audit-log-maxage argument is set to 30 or as appropriate | Scored | L1 | Equivalent Control |
| 1.2.24 | Ensure that the --audit-log-maxbackup argument is set to 10 or as appropriate | Scored | L1 | Equivalent Control |
| 1.2.25 | Ensure that the --audit-log-maxsize argument is set to 100 or as appropriate | Scored | L1 | Equivalent Control |
| 1.2.26 | Ensure that the --request-timeout argument is set as appropriate | Scored | L1 | Pass |
| 1.2.27 | Ensure that the --service-account-lookup argument is set to true | Scored | L1 | Pass |
| 1.2.28 | Ensure that the --service-account-key-file argument is set as appropriate | Scored | L1 | Pass |
| 1.2.29 | Ensure that the --etcd-certfile and --etcd-keyfile arguments are set as appropriate | Scored | L1 | Fail |
| 1.2.30 | Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate | Scored | L1 | Pass |
| 1.2.31 | Ensure that the --client-ca-file argument is set as appropriate | Scored | L1 | Pass |
| 1.2.32 | Ensure that the --etcd-cafile argument is set as appropriate | Scored | L1 | Fail |
| 1.2.33 | Ensure that the --encryption-provider-config argument is set as appropriate | Scored | L1 | Pass |
| 1.2.34 | Ensure that encryption providers are appropriately configured | Scored | L1 | Fail |
| 1.2.35 | Ensure that the API Server only makes use of Strong Cryptographic Ciphers | Not Scored | L1 | Pass |
| 1.3 | Controller Manager | |||
| 1.3.1 | Ensure that the --terminated-pod-gc-threshold argument is set as appropriate | Scored | L1 | Pass |
| 1.3.2 | Ensure that the --profiling argument is set to false | Scored | L1 | Fail |
| 1.3.3 | Ensure that the --use-service-account-credentials argument is set to true | Scored | L1 | Fail |
| 1.3.4 | Ensure that the --service-account-private-key-file argument is set as appropriate | Scored | L1 | Pass |
| 1.3.5 | Ensure that the --root-ca-file argument is set as appropriate | Scored | L1 | Pass |
| 1.3.6 | Ensure that the RotateKubeletServerCertificate argument is set to true | Scored | L2 | Equivalent Control |
| 1.3.7 | Ensure that the --bind-address argument is set to 127.0.0.1 | Scored | L1 | Pass |
| 1.4 | Scheduler | |||
| 1.4.1 | Ensure that the --profiling argument is set to false | Scored | L1 | Fail |
| 1.4.2 | Ensure that the --bind-address argument is set to 127.0.0.1 | Scored | L1 | Pass |
| 2 | etcd | |||
| 2.1 | Ensure that the --cert-file and --key-file arguments are set as appropriate | Scored | L1 | Fail |
| 2.2 | Ensure that the --client-cert-auth argument is set to true | Scored | L1 | Fail |
| 2.3 | Ensure that the --auto-tls argument is not set to true | Scored | L1 | Pass |
| 2.4 | Ensure that the --peer-cert-file and --peer-key-file arguments are set as appropriate | Scored | L1 | Equivalent Control |
| 2.5 | Ensure that the --peer-client-cert-auth argument is set to true | Scored | L1 | Equivalent Control |
| 2.6 | Ensure that the --peer-auto-tls argument is not set to true | Scored | L1 | Equivalent Control |
| 2.7 | Ensure that a unique Certificate Authority is used for etcd | Not Scored | L2 | Pass |
| 3 | Control Plane Configuration | |||
| 3.1 | Authentication and Authorization | |||
| 3.1.1 | Client certificate authentication should not be used for users | Not Scored | L2 | Pass |
| 3.2 | Logging | |||
| 3.2.1 | Ensure that a minimal audit policy is created | Scored | L1 | Pass |
| 3.2.2 | Ensure that the audit policy covers key security concerns | Not Scored | L2 | Pass |
| 4 | Worker Nodes | |||
| 4.1 | Worker Node Configuration Files | |||
| 4.1.1 | Ensure that the kubelet service file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 4.1.2 | Ensure that the kubelet service file ownership is set to root:root |
Scored | L1 | Pass |
| 4.1.3 | Ensure that the proxy kubeconfig file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 4.1.4 | Ensure that the proxy kubeconfig file ownership is set to root:root |
Scored | L1 | Pass |
| 4.1.5 | Ensure that the kubelet.conf file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 4.1.6 | Ensure that the kubelet.conf file ownership is set to root:root |
Scored | L1 | Pass |
| 4.1.7 | Ensure that the certificate authorities file permissions are set to 644 or more restrictive |
Scored | L1 | Pass |
| 4.1.8 | Ensure that the client certificate authorities file ownership is set to root:root |
Scored | L1 | Pass |
| 4.1.9 | Ensure that the kubelet configuration file has permissions set to 644 or more restrictive |
Scored | L1 | Pass |
| 4.1.10 | Ensure that the kubelet configuration file ownership is set to root:root |
Scored | L1 | Pass |
| 4.2 | Kubelet | |||
| 4.2.1 | Ensure that the --anonymous-auth argument is set to false | Scored | L1 | Pass |
| 4.2.2 | Ensure that the --authorization-mode argument is not set to AlwaysAllow | Scored | L1 | Pass |
| 4.2.3 | Ensure that the --client-ca-file argument is set as appropriate | Scored | L1 | Pass |
| 4.2.4 | Ensure that the --read-only-port argument is set to 0 | Scored | L1 | Fail |
| 4.2.5 | Ensure that the --streaming-connection-idle-timeout argument is not set to 0 | Scored | L1 | Pass |
| 4.2.6 | Ensure that the --protect-kernel-defaults argument is set to true | Scored | L1 | Fail |
| 4.2.7 | Ensure that the --make-iptables-util-chains argument is set to true | Scored | L1 | Pass |
| 4.2.8 | Ensure that the --hostname-override argument is not set | Not Scored | L1 | Pass |
| 4.2.9 | Ensure that the --event-qps argument is set to 0 or a level which ensures appropriate event capture | Not Scored | L2 | Fail |
| 4.2.10 | Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate | Scored | L1 | Equivalent Control |
| 4.2.11 | Ensure that the --rotate-certificates argument is not set to false | Scored | L1 | Equivalent Control |
| 4.2.12 | Ensure that the RotateKubeletServerCertificate argument is set to true | Scored | L1 | Equivalent Control |
| 4.2.13 | Ensure that the Kubelet only makes use of Strong Cryptographic Ciphers | Not Scored | L1 | Fail |
| 5 | Policies | |||
| 5.1 | RBAC and Service Accounts | |||
| 5.1.1 | Ensure that the cluster-admin role is only used where required | Not Scored | L1 | Depends on Environment |
| 5.1.2 | Minimize access to secrets | Not Scored | L1 | Depends on Environment |
| 5.1.3 | Minimize wildcard use in Roles and ClusterRoles | Not Scored | L1 | Depends on Environment |
| 5.1.4 | Minimize access to create pods | Not Scored | L1 | Depends on Environment |
| 5.1.5 | Ensure that default service accounts are not actively used | Scored | L1 | Depends on Environment |
| 5.1.6 | Ensure that Service Account Tokens are only mounted where necessary | Not Scored | L1 | Depends on Environment |
| 5.2 | Pod Security Policies | |||
| 5.2.1 | Minimize the admission of privileged containers | Not Scored | L1 | Depends on Environment |
| 5.2.2 | Minimize the admission of containers wishing to share the host process ID namespace | Scored | L1 | Depends on Environment |
| 5.2.3 | Minimize the admission of containers wishing to share the host IPC namespace | Scored | L1 | Depends on Environment |
| 5.2.4 | Minimize the admission of containers wishing to share the host network namespace | Scored | L1 | Depends on Environment |
| 5.2.5 | Minimize the admission of containers with allowPrivilegeEscalation | Scored | L1 | Depends on Environment |
| 5.2.6 | Minimize the admission of root containers | Not Scored | L2 | Depends on Environment |
| 5.2.7 | Minimize the admission of containers with the NET_RAW capability | Not Scored | L1 | Depends on Environment |
| 5.2.8 | Minimize the admission of containers with added capabilities | Not Scored | L1 | Depends on Environment |
| 5.2.9 | Minimize the admission of containers with capabilities assigned | Not Scored | L2 | Depends on Environment |
| 5.3 | Network Policies and CNI | |||
| 5.3.1 | Ensure that the CNI in use supports Network Policies | Not Scored | L1 | Pass |
| 5.3.2 | Ensure that all Namespaces have Network Policies defined | Scored | L2 | Depends on Environment |
| 5.4 | Secrets Management | |||
| 5.4.1 | Prefer using secrets as files over secrets as environment variables | Not Scored | L1 | Depends on Environment |
| 5.4.2 | Consider external secret storage | Not Scored | L2 | Depends on Environment |
| 5.5 | Extensible Admission Control | |||
| 5.5.1 | Configure Image Provenance using ImagePolicyWebhook admission controller | Not Scored | L2 | Depends on Environment |
| 5.6 | General Policies | |||
| 5.6.1 | Create administrative boundaries between resources using namespaces | Not Scored | L1 | Depends on Environment |
| 5.6.2 | Ensure that the seccomp profile is set to docker/default in your pod definitions | Not Scored | L2 | Depends on Environment |
| 5.6.3 | Apply Security Context to Your Pods and Containers | Not Scored | L2 | Depends on Environment |
| 5.6.4 | The default namespace should not be used | Scored | L2 | Depends on Environment |
Default values on GKE
Where the default for a new GKE cluster does not pass a recommendation from the CIS Kubernetes Benchmark, here are the default values used in GKE, with an explanation. Some of these recommendations can be remediated, following the remediation procedures laid out in the CIS GKE Benchmark. Items that can be automatically audited are marked as Scored in the CIS GKE Benchmark.
Default values for recommendations which Fail or Depends on Environment in a default GKE cluster:
| # | Recommendation | Scored/ Not Scored on CIS Kubernetes Benchmark |
Level | Default Status | Default Value | Justification | Scored/ Not Scored on CIS GKE Benchmark |
|---|---|---|---|---|---|---|---|
| 1 | Control Plane Components | ||||||
| 1.2 | API Server | ||||||
| 1.2.1 | Ensure that the --anonymous-auth argument is set to false | Not Scored | L1 | Fail | true |
Some GKE monitoring components use anonymous authentication to obtain metrics. Although GKE allows anonymous authentication for the kubelet, the exposure is identical to the read-only port as GKE disables the additional debugging handlers. | Not Scored |
| 1.2.3 | Ensure that the --token-auth-file parameter is not set | Scored | L1 | Fail | Set | Some control plane components are bootstrapped using static tokens, which are then used to authenticate to the API server. | Not Scored |
| 1.2.10 | Ensure that the admission control plugin EventRateLimit is set | Not Scored | L1 | Fail | Not set | GKE does not support the Event Rate Limit admission controller as it is a Kubernetes Alpha feature. | Not Scored |
| 1.2.12 | Ensure that the admission control plugin AlwaysPullImages is set | Not Scored | L1 | Fail | Not set | The AlwaysPullImages admission controller provides some protection for private registry images in noncooperative multitenant clusters, at the cost of making container registries a single-point-of-failure for creating new Pods across the entire cluster. GKE does not enable the AlwaysPullImages admission controller, which leaves it up to cluster admins to implement admission policy to make this tradeoff for themselves. | Not Scored |
| 1.2.13 | Ensure that the admission control plugin SecurityContextDeny is set if PodSecurityPolicy is not used | Not Scored | L1 | Fail | Not set | GKE does not enable the Security Context admission controller by default. Using a Pod Security Policy allows more control and is preferred. | Not Scored |
| 1.2.16 | Ensure that the admission control plugin PodSecurityPolicy is set | Scored | L1 | Fail | Not set | GKE does not enable the Pod Security Policy admission controller by default, as this requires a policy to be set. GKE customers can enable PodSecurityPolicy. | Not Scored, see also 6.10.3 |
| 1.2.21 | Ensure that the --profiling argument is set to false | Scored | L1 | Fail | Not set | GKE uses profiling for debugging. | Not Scored |
| 1.2.22 | Ensure that the --audit-log-path argument is set | Scored | L1 | Equivalent Control | Not set | GKE captures audit logs, but does not use these flags for auditing. See GKE Audit policy for more details. | Not Scored |
| 1.2.23 | Ensure that the --audit-log-maxage argument is set to 30 or as appropriate | Scored | L1 | Equivalent Control | Not set | GKE captures audit logs, but does not use these flags for auditing. See GKE Audit policy for more details. | Not Scored |
| 1.2.24 | Ensure that the --audit-log-maxbackup argument is set to 10 or as appropriate | Scored | L1 | Equivalent Control | Not set | GKE captures audit logs, but does not use these flags for auditing. See GKE Audit policy for more details. | Not Scored |
| 1.2.25 | Ensure that the --audit-log-maxsize argument is set to 100 or as appropriate | Scored | L1 | Equivalent Control | Not set | GKE captures audit logs, but does not use these flags for auditing. See GKE Audit policy for more details. | Not Scored |
| 1.2.29 | Ensure that the --etcd-certfile and --etcd-keyfile arguments are set as appropriate | Scored | L1 | Fail | Not set | GKE does not currently use mTLS to protect connections between the API server to etcd. Note that etcd listens on localhost. See Cluster trust for more details. | Not Scored |
| 1.2.32 | Ensure that the --etcd-cafile argument is set as appropriate | Scored | L1 | Fail | Not set | GKE does not currently use mTLS to protect connections between the API server to etcd. Note that etcd listens on localhost. See Cluster trust for more details. | Not Scored |
| 1.2.34 | Ensure that encryption providers are appropriately configured | Scored | L1 | Fail | identity |
GKE encrypts customer content at rest by default. To further encrypts secrets, use Application-layer Secrets Encryption. | Not Scored, see also 6.3.1 |
| 1.3 | Controller Manager | ||||||
| 1.3.2 | Ensure that the --profiling argument is set to false | Scored | L1 | Fail | true |
GKE uses profiling for debugging. | Not Scored |
| 1.3.6 | Ensure that the RotateKubeletServerCertificate argument is set to true | Scored | L2 | Equivalent Control | false |
GKE rotates kubelet certificates, but does not use this flag. | Not Scored |
| 1.4 | Scheduler | ||||||
| 1.4.1 | Ensure that the --profiling argument is set to false | Scored | L1 | Fail | true |
GKE uses profiling for debugging. | Not Scored |
| 2 | etcd | ||||||
| 2.1 | Ensure that the --cert-file and --key-file arguments are set as appropriate | Scored | L1 | Fail | Not set | GKE does not currently use mTLS to protect connections between the API server to etcd. Note that etcd listens on localhost. See Cluster trust for more details. | Not Scored |
| 2.2 | Ensure that the --client-cert-auth argument is set to true | Scored | L1 | Fail | Not set | GKE does not currently use mTLS to protect connections between the API server to etcd. Note that etcd listens on localhost. See Cluster trust for more details. | Not Scored |
| 2.4 | Ensure that the --peer-cert-file and --peer-key-file arguments are set as appropriate | Scored | L1 | Equivalent Control | Not set | GKE uses mTLS for peer traffic between instances of etcd. These flags are used for regional clusters but not zonal clusters, as there is only one instance of etcd in a zonal cluster. See Cluster trust for more details. | Not Scored |
| 2.5 | Ensure that the --peer-client-cert-auth argument is set to true | Scored | L1 | Equivalent Control | Not set | GKE uses mTLS for peer traffic between instances of etcd. These flags are used for regional clusters but not zonal clusters, as there is only one instance of etcd in a zonal cluster. See Cluster trust for more details. | Not Scored |
| 2.6 | Ensure that the --peer-auto-tls argument is not set to true | Scored | L1 | Equivalent Control | Not set | GKE uses mTLS for peer traffic between instances of etcd. These flags are used for regional clusters but not zonal clusters, as there is only one instance of etcd in a zonal cluster. See Cluster trust for more details. | Not Scored |
| 4 | Worker Nodes | ||||||
| 4.2 | Kubelet | ||||||
| 4.2.4 | Ensure that the --read-only-port argument is set to 0 | Scored | L1 | Fail | 10255 |
Some GKE monitoring components use the kubelet read-only port to obtain metrics. | Scored |
| 4.2.6 | Ensure that the --protect-kernel-defaults argument is set to true | Scored | L1 | Fail | false |
GKE doesn't protect kernel defaults from Kubernetes, as customer workloads may want to modify these. | Scored |
| 4.2.9 | Ensure that the --event-qps argument is set to 0 or a level which ensures appropriate event capture | Not Scored | L2 | Fail | 5 |
Events are Kubernetes objects stored in etcd. To avoid overwhelming etcd they are only kept for one hour, and are not an appropriate security auditing mechanism. Allowing unlimited events as suggested in this control exposes the cluster to unnecessary DoS risk and contradicts the recommendation to use admission EventRateLimits. Security relevant events that need permanent storage should be sent to logs. | Scored |
| 4.2.10 | Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate | Scored | L1 | Equivalent Control | Not Set | GKE uses mTLS for kubelet to API server traffic. GKE uses TLS for API server to kubelet traffic, which is authenticated for GKE v1.12+ clusters. GKE does not use these flags but rather this is specified in the kubelet config file. See Cluster trust for more details. | Scored |
| 4.2.11 | Ensure that the --rotate-certificates argument is not set to false | Scored | L1 | Equivalent Control | Not set | GKE rotates server certificates for GKE v1.12+ clusters. GKE does not use these flags but rather this is specified in the kubelet config file. GKE does not rotate client certificates, unless Shielded GKE Nodes are enabled. In this case, GKE does not use these flags but runs a separate process for certificate rotation. See Cluster trust for more details. | Scored |
| 4.2.12 | Ensure that the RotateKubeletServerCertificate argument is set to true | Scored | L1 | Equivalent Control | Not set | GKE rotates server certificates for GKE v1.12+ clusters. GKE does not use these flags but rather this is specified in the kubelet config file. See Cluster trust for more details. | Scored |
| 4.2.13 | Ensure that the kubelet only makes use of Strong Cryptographic Ciphers | Not Scored | Fail | Not set | GKE uses the golang default allowed cipher set, which is considered safe to use by the golang cryptography experts, and is also the default for Kubernetes. | Not Scored | |
| 5 | Policies | ||||||
| 5.1 | RBAC and Service Accounts | ||||||
| 5.1.1 | Ensure that the cluster-admin role is only used where required | Not Scored | L1 | Depends on Environment | n/a | Not Scored | |
| 5.1.2 | Minimize access to secrets | Not Scored | L1 | Depends on Environment | n/a | Not Scored | |
| 5.1.3 | Minimize wildcard use in Roles and ClusterRoles | Not Scored | L1 | Depends on Environment | n/a | Not Scored | |
| 5.1.4 | Minimize access to create pods | Not Scored | L1 | Depends on Environment | n/a | Not Scored | |
| 5.1.5 | Ensure that default service accounts are not actively used | Scored | L1 | Depends on Environment | n/a | Scored | |
| 5.1.6 | Ensure that Service Account Tokens are only mounted where necessary | Not Scored | L1 | Depends on Environment | n/a | Not Scored | |
| 5.2 | Pod Security Policies | ||||||
| 5.2.1 | Minimize the admission of privileged containers | Not Scored | L1 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.2.2 | Minimize the admission of containers wishing to share the host process ID namespace | Scored | L1 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.2.3 | Minimize the admission of containers wishing to share the host IPC namespace | Scored | L1 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.2.4 | Minimize the admission of containers wishing to share the host network namespace | Scored | L1 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.2.5 | Minimize the admission of containers with allowPrivilegeEscalation | Scored | L1 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.2.6 | Minimize the admission of root containers | Not Scored | L2 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.2.7 | Minimize the admission of containers with the NET_RAW capability | Not Scored | L1 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.2.8 | Minimize the admission of containers with added capabilities | Not Scored | L1 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.2.9 | Minimize the admission of containers with capabilities assigned | Not Scored | L2 | Depends on Environment | n/a | No Pod Security Policy is set by default. | Scored |
| 5.3 | Network Policies and CNI | ||||||
| 5.3.2 | Ensure that all Namespaces have Network Policies defined | Scored | L2 | Depends on Environment | n/a | Scored | |
| 5.4 | Secrets Management | ||||||
| 5.4.1 | Prefer using secrets as files over secrets as environment variables | Not Scored | L1 | Depends on Environment | n/a | Not Scored | |
| 5.4.2 | Consider external secret storage | Not Scored | L2 | Depends on Environment | n/a | Not Scored | |
| 5.5 | Extensible Admission Control | ||||||
| 5.5.1 | Configure Image Provenance using ImagePolicyWebhook admission controller | Not Scored | L2 | Depends on Environment | Not enabled | GKE does not enable the Image Policy Webhook admission controller by default. Image Provenance using Binary Authorization is not set by default, as this requires a policy to be set. | Not Scored, see also 6.10.5 |
| 5.6 | General Policies | ||||||
| 5.6.1 | Create administrative boundaries between resources using namespaces | Not Scored | L1 | Depends on Environment | n/a | Not Scored | |
| 5.6.2 | Ensure that the seccomp profile is set to docker/default in your pod definitions | Not Scored | L2 | Depends on Environment | n/a | No seccomp profile is set by default. | Not Scored |
| 5.6.3 | Apply Security Context to Your Pods and Containers | Not Scored | L2 | Depends on Environment | n/a | No Security Context is set by default. | Not Scored |
| 5.6.4 | The default namespace should not be used | Scored | L2 | Depends on Environment | n/a | Scored |
CIS GKE Benchmark
Accessing the Benchmark
The CIS GKE Benchmark is available on the CIS website:
- Go to the full list of CIS Benchmarks.
- Under the Kubernetes heading, click Expand to see related content.
- The CIS GKE Benchmark is listed for download.
Recommendation Levels
In the CIS GKE Benchmark,
| Level | Description |
|---|---|
| Level 1 | Recommendations are meant to be widely applicable. These should be applied to almost all environments. |
| Level 2 | Recommendations result in a more stringent security environment, but are not necessarily applicable to all cases. These may have performance impact, or may not be able to be applied in concert with other recommendations. These should be evaluated for your environment before being applied. In some cases, for example multi-tenant workloads, these recommendations may be more relevant. |
Recommendation scoring
In the CIS GKE Benchmark,
| Scoring | Description |
|---|---|
| Scored |
Recommendations are easily tested using an automated method, and has a value that can be definitively evaluated. These recommendations only include Generally Available products or features. |
| Not Scored |
Recommendations cannot be easily assessed using automation or requires evaluation to determine the exact implementation appropriate for your workload. These recommendations may use Beta products or features. For example, Pod Security Policy requires the use of a policy specific to your workload, and is a Beta feature, so is Not Scored. |
Evaluation on GKE
For GKE-specific recommendations (section 6), since these are all configurable such that they can be configured to Pass in your environment, we use the following values to specify the default values:
| Status | Description |
|---|---|
| Default | A new cluster complies with a Benchmark recommendation by default. |
| Not Default | A new cluster does not comply with a Benchmark recommendation by default. |
| Depends on Environment | GKE does not configure items related to this Recommendation. The user's configuration determines whether their environment complies with a Benchmark recommendation. |
Default values on GKE
When creating a new GKE cluster with the specified version, here's how it will perform against the CIS Kubernetes Benchmark.
Status of default GKE cluster:
| # | Recommendation | Scored/ Not Scored | Level | Default Status |
|---|---|---|---|---|
| 6 | Managed services | |||
| 6.1 | Image Registry and Image Scanning | |||
| 6.1.1 | Ensure Image Vulnerability Scanning using GCR Container Analysis or a third party provider | Scored | L1 | Not Default |
| 6.1.2 | Minimize user access to GCR | Scored | L1 | Depends on Environment |
| 6.1.3 | Minimize cluster access to read-only for GCR | Scored | L1 | Not Default |
| 6.1.4 | Minimize Container Registries to only those approved | Not Scored | L2 | Not Default |
| 6.2 | Identity and Access Management (IAM) | |||
| 6.2.1 | Prefer not running GKE clusters using the Compute Engine default service account | Scored | L2 | Not Default |
| 6.2.2 | Prefer using dedicated Google Cloud Service Accounts and Workload Identity | Not Scored | L1 | Not Default |
| 6.3 | Cloud Key Management Service (Cloud KMS) | |||
| 6.3.1 | Consider encrypting Kubernetes Secrets using keys managed in Cloud KMS | Scored | L1 | Not Default |
| 6.4 | Node Metadata | |||
| 6.4.1 | Ensure legacy Compute Engine instance metadata APIs are Disabled | Scored | L1 | Default |
| 6.4.2 | Ensure the GKE Metadata Server is Enabled | Not Scored | L2 | Not Default |
| 6.5 | Node Configuration and Maintenance | |||
| 6.5.1 | Ensure Container-Optimized OS (COS) is used for GKE node images | Scored | L2 | Default |
| 6.5.2 | Ensure Node Auto-Repair is enabled for GKE nodes | Scored | L1 | Default |
| 6.5.3 | Ensure Node Auto-Upgrade is enabled for GKE nodes | Scored | L1 | Default |
| 6.5.4 | Consider automating GKE version management using Release Channels | Not Scored | L1 | Not Default |
| 6.5.5 | Ensure Shielded GKE Nodes are Enabled | Not Scored | L1 | Not Default |
| 6.5.6 | Ensure Integrity Monitoring for Shielded GKE Nodes is Enabled | Not Scored | L1 | Not Default |
| 6.5.7 | Ensure Secure Boot for Shielded GKE Nodes is Enabled | Not Scored | L2 | Not Default |
| 6.6 | Cluster Networking | |||
| 6.6.1 | Consider enabling VPC Flow Logs and Intranode Visibility | Not Scored | L2 | Not Default |
| 6.6.2 | Prefer VPC-native clusters | Scored | L1 | Not Default |
| 6.6.3 | Ensure Master Authorized Networks is Enabled | Scored | L1 | Not Default |
| 6.6.4 | Ensure clusters are created with Private Endpoint Enabled and Public Access Disabled | Scored | L2 | Not Default |
| 6.6.5 | Ensure clusters are created with Private Nodes | Scored | L1 | Not Default |
| 6.6.6 | Consider firewalling GKE worker nodes | Not Scored | L1 | Not Default |
| 6.6.7 | Ensure Network Policy is Enabled and set as appropriate | Not Scored | L1 | Not Default |
| 6.6.8 | Consider using Google-managed SSL Certificates | Not Scored | L2 | Depends on Environment |
| 6.7 | Logging | |||
| 6.7.1 | Ensure Stackdriver Kubernetes Logging and Monitoring is Enabled | Scored | L1 | Default |
| 6.7.2 | Consider enabling Linux auditd logging | Not Scored | L2 | Not Default |
| 6.8 | Authentication and Authorization | |||
| 6.8.1 | Ensure Basic Authentication using static passwords is Disabled | Scored | L1 | Default |
| 6.8.2 | Ensure authentication using Client Certificates is Disabled | Scored | L1 | Default |
| 6.8.3 | Consider managing Kubernetes RBAC users with Google Groups for RBAC | Not Scored | L2 | Not Default |
| 6.8.4 | Ensure Legacy Authorization (ABAC) is Disabled | Scored | L1 | Default |
| 6.9 | Storage | |||
| 6.9.1 | Consider enabling Customer-Managed Encryption Keys (CMEK) for GKE persistent disks (PDs) | Not Scored | L1 | Not Default |
| 6.10 | Other Cluster Configurations | |||
| 6.10.1 | Ensure Kubernetes Web UI is Disabled | Scored | L1 | Default |
| 6.10.2 | Ensure that Alpha clusters are not used for production workloads | Scored | L1 | Default |
| 6.10.3 | Ensure Pod Security Policy is Enabled and set as appropriate | Not Scored | L1 | Not Default |
| 6.10.4 | Consider GKE Sandbox for running untrusted workloads | Not Scored | L2 | Not Default |
| 6.10.5 | Prefer enabling Binary Authorization and configuring policy as appropriate | Not Scored | L2 | Not Default |
| 6.10.6 | Prefer enabling Cloud Security Command Center (Cloud SCC) | Not Scored | L1 | Not Default |
How to audit Benchmarks
Specific instructions for auditing each recommendation is available as part of the relevant CIS Benchmark. However, you may wish to automate some of these checks to simplify the verification of these controls in your environment. The tools listed below can help with this.
Note that this does not allow you to audit recommendations from the Kubernetes CIS Benchmark that are not auditable on GKE. For components that you cannot directly audit, see Default values to understand how your environment is already configured by GKE.
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. Note
that you will be unable to run the kube-bench master tests against your
GKE workloads, since you do not have access to the control plane
node directly; and will only be able to run the kube-bench node tests.
Make sure to specify the appropriate version, for example:
kube-bench node --benchmark cis-1.5
Automated auditing of the CIS GKE Benchmark
Security Health Analytics identifies common misconfigurations in your environment, such as open firewalls or public buckets. This includes GKE security recommendations. By enabling Security Health Analytics, you'll be notified of cluster misconfigurations you may have in Cloud Security Command Center.
Many Level 1 Scored recommendations are covered by corresponding findings in Security Health Analytics.
| # | Recommendation | Scored/ Not Scored | Level | Security Health Analytics Finding(s) |
|---|---|---|---|---|
| 6.1 | Image Registry and Image Scanning | |||
| 6.1.1 | Ensure Image Vulnerability Scanning using GCR Container Analysis or a third party provider | Scored | L1 | n/a |
| 6.1.2 | Minimize user access to GCR | Scored | L1 | n/a |
| 6.1.3 | Minimize cluster access to read-only for GCR | Scored | L1 | n/a |
| 6.1.4 | Minimize Container Registries to only those approved | Not Scored | L2 | n/a |
| 6.2 | Identity and Access Management (IAM) | |||
| 6.2.1 | Prefer not running GKE clusters using the Compute Engine default service account | Scored | L2 | OVER_PRIVILEGED_ACCOUNT and OVER_PRIVILEGED_SCOPES |
| 6.2.2 | Prefer using dedicated Google Cloud Service Accounts and Workload Identity | Not Scored | L1 | WORKLOAD_IDENTITY_DISABLED |
| 6.3 | Cloud Key Management Service (Cloud KMS) | |||
| 6.3.1 | Consider encrypting Kubernetes Secrets using keys managed in Cloud KMS | Scored | L1 | n/a |
| 6.4 | Node Metadata | |||
| 6.4.1 | Ensure legacy Compute Engine instance metadata APIs are Disabled | Scored | L1 | LEGACY_METADATA_ENABLED |
| 6.4.2 | Ensure the GKE Metadata Server is Enabled | Not Scored | L2 | n/a |
| 6.5 | Node Configuration and Maintenance | |||
| 6.5.1 | Ensure Container-Optimized OS (COS) is used for GKE node images | Scored | L2 | COS_NOT_USED |
| 6.5.2 | Ensure Node Auto-Repair is enabled for GKE nodes | Scored | L1 | AUTO_REPAIR_DISABLED |
| 6.5.3 | Ensure Node Auto-Upgrade is enabled for GKE nodes | Scored | L1 | AUTO_UPGRADE_DISABLED |
| 6.5.4 | Consider automating GKE version management using Release Channels | Not Scored | L1 | n/a |
| 6.5.5 | Ensure Shielded GKE Nodes are Enabled | Not Scored | L1 | n/a |
| 6.5.6 | Ensure Integrity Monitoring for Shielded GKE Nodes is Enabled | Not Scored | L1 | n/a |
| 6.5.7 | Ensure Secure Boot for Shielded GKE Nodes is Enabled | Not Scored | L2 | n/a |
| 6.6 | Cluster Networking | |||
| 6.6.1 | Consider enabling VPC Flow Logs and Intranode Visibility | Not Scored | L2 | FLOW_LOGS_DISABLED |
| 6.6.2 | Prefer VPC-native clusters | Scored | L1 | IP_ALIAS_DISABLED |
| 6.6.3 | Ensure Master Authorized Networks is Enabled | Scored | L1 | MASTER_AUTHORIZED_NETWORKS_DISABLED |
| 6.6.4 | Ensure clusters are created with Private Endpoint Enabled and Public Access Disabled | Scored | L2 | n/a |
| 6.6.5 | Ensure clusters are created with Private Nodes | Scored | L1 | PRIVATE_CLUSTER_DISABLED |
| 6.6.6 | Consider firewalling GKE worker nodes | Not Scored | L1 | n/a |
| 6.6.7 | Ensure Network Policy is Enabled and set as appropriate | Not Scored | L1 | NETWORK_POLICY_DISABLED |
| 6.6.8 | Consider using Google-managed SSL Certificates | Not Scored | L2 | n/a |
| 6.7 | Logging | |||
| 6.7.1 | Ensure Stackdriver Kubernetes Logging and Monitoring is Enabled | Scored | L1 | CLUSTER_LOGGING_DISABLED and CLUSTER_MONITORING_DISABLED |
| 6.7.2 | Consider enabling Linux auditd logging | Not Scored | L2 | n/a |
| 6.8 | Authentication and Authorization | |||
| 6.8.1 | Ensure Basic Authentication using static passwords is Disabled | Scored | L1 | n/a |
| 6.8.2 | Ensure authentication using Client Certificates is Disabled | Scored | L1 | n/a |
| 6.8.3 | Consider managing Kubernetes RBAC users with Google Groups for RBAC | Not Scored | L2 | n/a |
| 6.8.4 | Ensure Legacy Authorization (ABAC) is Disabled | Scored | L1 | LEGACY_AUTHORIZATION_ENABLED |
| 6.9 | Storage | |||
| 6.9.1 | Consider enabling Customer-Managed Encryption Keys (CMEK) for GKE persistent disks (PDs) | Not Scored | L1 | n/a |
| 6.10 | Other Cluster Configurations | |||
| 6.10.1 | Ensure Kubernetes Web UI is Disabled | Scored | L1 | WEB_UI_ENABLED |
| 6.10.2 | Ensure that Alpha clusters are not used for production workloads | Scored | L1 | n/a |
| 6.10.3 | Ensure Pod Security Policy is Enabled and set as appropriate | Not Scored | L1 | POD_SECURITY_POLICY_DISABLED |
| 6.10.4 | Consider GKE Sandbox for running untrusted workloads | Not Scored | L2 | n/a |
| 6.10.5 | Prefer enabling Binary Authorization and configuring policy as appropriate | Not Scored | L2 | n/a |
| 6.10.6 | Prefer enabling Cloud Security Command Center (Cloud SCC) | Not Scored | L1 | n/a |
What's next
- Read the GKE security overview.
- Follow security best practices in the GKE hardening guide.
- Learn more about the shared responsibility model in GKE.