CIS Kubernetes Benchmark v1.23 - RKE2
https://docs.rke2.io/security/cis_self_assessment123
CIS Kubernetes Benchmark v1.23 - RKE2
Overview
This document is a companion to the RKE2 security hardening guide. The hardening guide provides prescriptive guidance for hardening a production installation of RKE2, and this benchmark guide is meant to help you evaluate the level of security of the hardened cluster against each control in the CIS Kubernetes benchmark. It is to be used by RKE2 operators, security teams, auditors, and decision makers.
This guide is specific to the v1.25 release line of RKE2 and the v1.23 release of the CIS Kubernetes Benchmark.
For more details about each control, including detailed descriptions and remediations for failing tests, you can refer to the corresponding section of the CIS Kubernetes Benchmark v1.23 You can download the benchmark after logging in to CISecurity.org.
Testing controls methodology
Each control in the CIS Kubernetes Benchmark was evaluated against an RKE2 cluster that was configured according to the accompanying hardening guide.
Where control audits differ from the original CIS benchmark, the audit commands specific to RKE2 are provided for testing.
These are the possible results for each control:
Pass - The RKE2 cluster under test passed the audit outlined in the benchmark.
Not Applicable - The control is not applicable to RKE2 because of how it is designed to operate. The remediation section will explain why this is so.
Manual - Operator Dependent - The control is Manual in the CIS benchmark and it depends on the cluster's use case or some other factor that must be determined by the cluster operator. These controls have been evaluated to ensure RKE2 does not prevent their implementation, but no further configuration or auditing of the cluster under test has been performed.
Controls
1 Master Node Security Configuration
1.1 Master Node Configuration Files
1.1.1
Ensure that the API server pod specification file permissions are set to 644 or more restrictive (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates these files with 644 permissions. No manual remediation needed.
1.1.2
Ensure that the API server pod specification file ownership is set to root:root (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates these files with root:root ownership. No manual remediation needed.
1.1.3
Ensure that the controller manager pod specification file permissions are set to 644 or more restrictive (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates these files with 644 permissions. No manual remediation needed.
1.1.4
Ensure that the controller manager pod specification file ownership is set to root:root (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates these files with root:root ownership. No manual remediation needed.
1.1.5
Ensure that the scheduler pod specification file permissions are set to 644 or more restrictive (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates these files with 644 permissions. No manual remediation needed.
1.1.6
Ensure that the scheduler pod specification file ownership is set to root:root (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates these files with root:root ownership. No manual remediation needed.
1.1.7
Ensure that the etcd pod specification file permissions are set to 644 or more restrictive (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates these files with 644 permissions. No manual remediation needed.
1.1.8
Ensure that the etcd pod specification file ownership is set to root:root (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates these files with root:root ownership. No manual remediation needed.
1.1.9
Ensure that the Container Network Interface file permissions are set to 644 or more restrictive (Manual)
Result: Pass
Audit:
Remediation: RKE2 deploys the default CNI, Canal, using a Helm chart. The chart is defined as a custom resource in a file with 644 permissions. No manual remediation needed.
1.1.10
Ensure that the Container Network Interface file ownership is set to root:root (Manual)
Result: Pass
Audit:
Remediation: RKE2 deploys the default CNI, Canal, using a Helm chart. The chart is defined as a custom resource in a file with root:root ownership. No manual remediation needed.
1.1.11
Ensure that the etcd data directory permissions are set to 700 or more restrictive (Automated)
Result: Pass
Audit:
Remediation: RKE2 manages the etcd data directory and sets its permissions to 700. No manual remediation needed.
1.1.12
Ensure that the etcd data directory ownership is set to etcd:etcd (Automated)
Result: Pass
Audit:
Remediation: When running RKE2 with the profile flag set to cis-1.23, RKE2 will refuse to start if the etcd user and group doesn't exist on the host. If it does exist, RKE2 will automatically set the ownership of the etcd data directory to etcd:etcd and ensure the etcd static pod is started with that user and group.
1.1.13
Ensure that the admin.conf file permissions are set to 644 or more restrictive (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates this file at /var/lib/rancher/rke2/server/cred/admin.kubeconfig and automatically sets its permissions to 644. No manual remediation needed.
1.1.14
Ensure that the admin.conf file ownership is set to root:root (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates this file at stat -c %U:%G /var/lib/rancher/rke2/server/cred/admin.kubeconfig and automatically sets its ownership to root:root.
1.1.15
Ensure that the scheduler.conf file permissions are set to 644 or more restrictive (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates this file at /var/lib/rancher/rke2/server/cred/scheduler.kubeconfig and automatically sets its permissions to 644. No manual remediation needed.
1.1.16
Ensure that the scheduler.conf file ownership is set to root:root (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates this file at /var/lib/rancher/rke2/server/cred/scheduler.kubeconfig and automatically sets its ownership to root:root.
1.1.17
Ensure that the controller.kubeconfig file permissions are set to 644 or more restrictive (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates this file at /var/lib/rancher/rke2/server/cred/controller.kubeconfig and automatically sets its permissions to 644. No manual remediation needed.
1.1.18
Ensure that the controller.kubeconfig file ownership is set to root:root (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates this file at /var/lib/rancher/rke2/server/cred/controller.kubeconfig and automatically sets its ownership to root:root.
1.1.19
Ensure that the Kubernetes PKI directory and file ownership is set to root:root (Automated)
Result: Pass
Audit:
Remediation: By default, RKE2 creates the directory and files with the expected ownership of root:root. No manual remediation should be necessary.
1.1.20
Ensure that the Kubernetes PKI certificate file permissions are set to 644 or more restrictive (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the permissions are 644 or more restrictive.
Remediation: By default, RKE2 creates the files with the expected permissions of 644. No manual remediation is needed.
1.1.21
Ensure that the Kubernetes PKI key file permissions are set to 600 (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the permissions are 600 or more restrictive.
Remediation: By default, RKE2 creates the files with the expected permissions of 600. No manual remediation is needed.
1.2 API Server
This section contains recommendations relating to API server configuration flags
1.2.1
Ensure that the --anonymous-auth argument is set to false (Manual)
Result: Pass
Audit: Run the below command on the master node.
Verify that --anonymous-auth=false is present.
Remediation: By default, RKE2 kube-apiserver is configured to run with this flag and value. No manual remediation is needed.
1.2.2
Ensure that the --token-auth-file parameter is not set (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --token-auth-file argument does not exist.
Remediation: By default, RKE2 does not run with token authentication enabled. No manual remediation is needed.
1.2.3
Ensure that the --DenyServiceExternalIPs is not set (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --enable-admission-plugins argument does not have DenyServiceExternalIPs.
Remediation: By default, RKE2 does not set DenyServiceExternalIPs to the admission plugin flag. No manual remediation is needed.
1.2.4
Ensure that the --kubelet-https argument is set to true (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --kubelet-https argument does not exist.
Remediation: By default, RKE2 kube-apiserver doesn't run with the --kubelet-https parameter as it runs with TLS. No manual remediation is needed.
1.2.5
Ensure that the --kubelet-client-certificate and --kubelet-client-key arguments are set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --kubelet-client-certificate and --kubelet-client-key arguments exist and they are set as appropriate.
Remediation: By default, RKE2 kube-apiserver is ran with these arguments for secure communication with kubelet. No manual remediation is needed.
1.2.6
Ensure that the --kubelet-certificate-authority argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --kubelet-certificate-authority argument exists and is set as appropriate.
Remediation: By default, RKE2 kube-apiserver is ran with this argument for secure communication with kubelet. No manual remediation is needed.
1.2.7
Ensure that the --authorization-mode argument is not set to AlwaysAllow (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the argument value doesn't contain AlwaysAllow.
Remediation: By default, RKE2 sets Node,RBAC as the parameter to the --authorization-mode argument. No manual remediation is needed.
1.2.8
Ensure that the --authorization-mode argument includes Node (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify Node exists as a parameter to the argument.
Remediation: By default, RKE2 sets Node,RBAC as the parameter to the --authorization-mode argument. No manual remediation is needed.
1.2.9
Ensure that the --authorization-mode argument includes RBAC (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify RBAC exists as a parameter to the argument.
Remediation: By default, RKE2 sets Node,RBAC as the parameter to the --authorization-mode argument. No manual remediation is needed.
1.2.10
Ensure that the admission control plugin EventRateLimit is set (Manual)
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
Verify that the --enable-admission-plugins argument is set to a value that includes EventRateLimit.
Remediation: By default, RKE2 only sets NodeRestriction,PodSecurityPolicy as the parameter to the --enable-admission-plugins argument. To configure this, follow the Kubernetes documentation and set the desired limits in a configuration file. Then refer to RKE2's documentation to see how to supply additional api server configuration via the kube-apiserver-arg parameter.
1.2.11
Ensure that the admission control plugin AlwaysAdmit is not set (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that if the --enable-admission-plugins argument is set, its value does not include AlwaysAdmit.
Remediation: By default, RKE2 only sets NodeRestriction,PodSecurityPolicy as the parameter to the --enable-admission-plugins argument. No manual remediation needed.
1.2.12
Ensure that the admission control plugin AlwaysPullImages is set (Manual)
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
Verify that the --enable-admission-plugins argument is set to a value that includes AlwaysPullImages.
Remediation: By default, RKE2 only sets NodeRestriction,PodSecurityPolicy as the parameter to the --enable-admission-plugins argument. To configure this, follow the Kubernetes documentation and set the desired limits in a configuration file. Then refer to RKE2's documentation to see how to supply additional api server configuration via the kube-apiserver-arg parameter.
1.2.13
Ensure that the admission control plugin SecurityContextDeny is set if PodSecurityPolicy is not used (Manual)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --enable-admission-plugins argument is set to a value that includes SecurityContextDeny, if PodSecurityPolicy is not included.
Remediation: By default, RKE2 automatically enables the PodSecurityPolicy admission plugin. Therefore, the SecurityContextDeny plugin need not be enabled. No manual remediation needed.
1.2.14
Ensure that the admission control plugin ServiceAccount is set (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --disable-admission-plugins argument is set to a value that does not includes ServiceAccount.
Remediation: By default, RKE2 does not use this argument. If there's a desire to use this argument, follow the documentation and create ServiceAccount objects as per your environment. Then refer to RKE2's documentation to see how to supply additional api server configuration via the kube-apiserver-arg parameter.
1.2.15
Ensure that the admission control plugin NamespaceLifecycle is set (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --disable-admission-plugins argument is set to a value that does not include NamespaceLifecycle.
Remediation: By default, RKE2 does not use this argument. No manual remediation needed.
1.2.16
Ensure that the admission control plugin NodeRestriction is set (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --enable-admission-plugins argument is set to a value that includes NodeRestriction.
Remediation: By default, RKE2 only sets NodeRestriction as the parameter to the --enable-admission-plugins argument. No manual remediation needed.
1.2.17
Ensure that the --secure-port argument is not set to 0 (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --secure-port argument is either not set or is set to an integer value between 1 and 65535.
Remediation: By default, RKE2 sets the parameter of 6443 for the --secure-port argument. No manual remediation is needed.
1.2.18
Ensure that the --profiling argument is set to false (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --profiling argument is set to false.
Remediation: By default, RKE2 sets the --profiling flag parameter to false. No manual remediation needed.
1.2.19
Ensure that the --audit-log-path argument is set (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --audit-log-path argument is set as appropriate.
Remediation: By default, RKE2 sets the --audit-log-path argument and parameter. No manual remediation needed.
1.2.20
Ensure that the --audit-log-maxage argument is set to 30 or as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --audit-log-maxage argument is set to 30 or as appropriate.
Remediation: By default, RKE2 sets the --audit-log-maxage argument parameter to 30. No manual remediation needed.
1.2.21
Ensure that the --audit-log-maxbackup argument is set to 10 or as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --audit-log-maxbackup argument is set to 10 or as appropriate.
Remediation: By default, RKE2 sets the --audit-log-maxbackup argument parameter to 10. No manual remediation needed.
1.2.22
Ensure that the --audit-log-maxsize argument is set to 100 or as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --audit-log-maxsize argument is set to 100 or as appropriate.
Remediation: By default, RKE2 sets the --audit-log-maxsize argument parameter to 100. No manual remediation needed.
1.2.23
Ensure that the --request-timeout argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --request-timeout argument is either not set or set to an appropriate value.
Remediation: By default, RKE2 does not set the --request-timeout argument. No manual remediation needed.
1.2.24
Ensure that the --service-account-lookup argument is set to true (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that if the --service-account-lookup argument exists it is set to true.
Remediation: By default, RKE2 doesn't set this argument in favor of taking the default effect. No manual remediation needed.
1.2.25
Ensure that the --service-account-key-file argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --service-account-key-file argument exists and is set as appropriate.
Remediation: By default, RKE2 sets the --service-account-key-file explicitly. No manual remediation needed.
1.2.26
Ensure that the --etcd-certfile and --etcd-keyfile arguments are set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --etcd-certfile and --etcd-keyfile arguments exist and they are set as appropriate.
Remediation: By default, RKE2 sets the --etcd-certfile and --etcd-keyfile arguments explicitly. No manual remediation needed.
1.2.27
Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --tls-cert-file and --tls-private-key-file arguments exist and they are set as appropriate.
Remediation: By default, RKE2 sets the --tls-cert-file and --tls-private-key-file arguments explicitly. No manual remediation needed.
1.2.28
Ensure that the --client-ca-file argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --client-ca-file argument exists and it is set as appropriate.
Remediation: By default, RKE2 sets the --client-ca-file argument explicitly. No manual remediation needed.
1.2.29
Ensure that the --etcd-cafile argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --etcd-cafile argument exists and it is set as appropriate.
Remediation: By default, RKE2 sets the --etcd-cafile argument explicitly. No manual remediation needed.
1.2.30
Ensure that the --encryption-provider-config argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --encryption-provider-config argument is set to a EncryptionConfigfile. Additionally, ensure that the EncryptionConfigfile has all the desired resources covered especially any secrets.
Remediation: By default, RKE2 sets the --encryption-provider-config argument explicitly. No manual remediation needed. RKE2's default encryption provider config file is located at /var/lib/rancher/rke2/server/cred/encryption-config.json and is configured to encrypt secrets.
1.2.31
Ensure that encryption providers are appropriately configured (Automated)
Result: Pass
Remediation: Follow the Kubernetes documentation and configure a EncryptionConfig file. In this file, choose aescbc, kms or secretbox as the encryption provider.
Audit: Run the below command on the master node.
Run the below command on the master node.
Verify that aescbc is set as the encryption provider for all the desired resources.
Remediation By default, RKE2 sets the argument --encryption-provider-config and parameter. The contents of the config file indicates the use of aescbc. No manual remediation needed.
1.2.32
Ensure that the API Server only makes use of Strong Cryptographic Ciphers (Manual)
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
Verify that the --tls-cipher-suites argument is set as outlined in the remediation procedure below.
Remediation: By default, RKE2 explicitly doesn't set this flag. No manual remediation needed.
1.3 Controller Manager
1.3.1
Ensure that the --terminated-pod-gc-threshold argument is set as appropriate (Manual)
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
Verify that the --terminated-pod-gc-threshold argument is set as appropriate.
Remediation: By default, RKE2 sets the --terminated-pod-gc-threshold argument with a value of 1000. No manual remediation needed.
1.3.2
Ensure that the --profiling argument is set to false (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --profiling argument is set to false.
Remediation: By default, RKE2 sets the --profiling flag parameter to false. No manual remediation needed.
1.3.3
Ensure that the --use-service-account-credentials argument is set to true (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --use-service-account-credentials argument is set to true.
Remediation: By default, RKE2 sets the --use-service-account-credentials argument to true. No manual remediation needed.
1.3.4
Ensure that the --service-account-private-key-file argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --service-account-private-key-file argument is set as appropriate.
Remediation: By default, RKE2 sets the --service-account-private-key-file argument with the service account key file. No manual remediation needed.
1.3.5
Ensure that the --root-ca-file argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --root-ca-file argument exists and is set to a certificate bundle file containing the root certificate for the API server's serving certificate
Remediation: By default, RKE2 sets the --root-ca-file argument with the root ca file. No manual remediation needed.
1.3.6
Ensure that the RotateKubeletServerCertificate argument is set to true (Automated)
Result: Not Applicable
Audit: Run the below command on the master node.
Verify that RotateKubeletServerCertificateargument exists and is set to true.
Remediation: By default, RKE2 implements it's own logic for certificate generation and rotation.
1.3.7
Ensure that the --bind-address argument is set to 127.0.0.1 (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --bind-address argument is set to 127.0.0.1.
Remediation: By default, RKE2 sets the --bind-address argument to 127.0.0.1. No manual remediation needed.
1.4 Scheduler
This section contains recommendations relating to Scheduler configuration flags
1.4.1
Ensure that the --profiling argument is set to false (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --profiling argument is set to false.
Remediation: By default, RKE2 sets the --profiling flag parameter to false. No manual remediation needed.
1.4.2
Ensure that the --bind-address argument is set to 127.0.0.1 (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --bind-address argument is set to 127.0.0.1.
Remediation: By default, RKE2 sets the --bind-address argument to 127.0.0.1. No manual remediation needed.
2 Etcd Node Configuration
This section covers recommendations for etcd configuration.
2.1
Ensure that the cert-file and key-file fields are set as appropriate (Automated)
Result: Not Applicable
Audit: Run the below command on the master node.
Verify that the cert-file and the key-file fields are set as appropriate.
Remediation: By default, RKE2 uses a config file for etcd that can be found at /var/lib/rancher/rke2/server/db/etcd/config. Server and peer cert and key files are specified. No manual remediation needed.
2.2
Ensure that the client-cert-auth field is set to true (Automated)
Result: Not Applicable
Audit: Run the below command on the master node.
Verify that the client-cert-auth field is set to true.
Remediation: By default, RKE2 uses a config file for etcd that can be found at /var/lib/rancher/rke2/server/db/etcd/config. client-cert-auth is set to true. No manual remediation needed.
2.3
Ensure that the auto-tls field is not set to true (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that if the auto-tls field does not exist.
Remediation: By default, RKE2 uses a config file for etcd that can be found at /var/lib/rancher/rke2/server/db/etcd/config. Within the file, it does not contain the auto-tls argument. No manual remediation needed.
2.4
Ensure that the peer-cert-file and peer-key-file fields are set as appropriate (Automated)
Result: Not Applicable
Audit: Run the below command on the master node.
Verify that the peer-server-client.crt and peer-server-client.key fields are set as appropriate.
Remediation: By default, RKE2 uses a config file for etcd that can be found at /var/lib/rancher/rke2/server/db/etcd/config. Within the file, the peer-server-client.crt and peer-server-client.key fields are set. No manual remediation needed.
2.5
Ensure that the peer-client-cert-auth argument is set to true (Automated)
Result: Not Applicable
Audit: Run the below command on the master node.
Verify that the peer-client-cert-auth field in the peer section is set to true.
Remediation: By default, RKE2 uses a config file for etcd that can be found at /var/lib/rancher/rke2/server/db/etcd/config. Within the file, the client-cert-auth field is set. No manual remediation needed.
2.6
Ensure that the peer-auto-tls field is not set to true (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that if the peer-auto-tls field does not exist.
Remediation: By default, RKE2 uses a config file for etcd that can be found at /var/lib/rancher/rke2/server/db/etcd/config. Within the file, it does not contain the peer-auto-tls field. No manual remediation needed.
2.7
Ensure that a unique Certificate Authority is used for etcd (Manual)
Result: Pass
Audit: Run the below command on the master node.
Verify that the file referenced by the client-ca-file flag in the apiserver process is different from the file referenced by the trusted-ca-file parameter in the etcd configuration file.
Remediation: By default, RKE2 uses a config file for etcd that can be found at /var/lib/rancher/rke2/server/db/etcd/config and the trusted-ca-file parameters in it are set to unique values specific to etcd. No manual remediation needed.
3 Control Plane Configuration
3.1 Authentication and Authorization
3.1.1
Client certificate authentication should not be used for users (Manual)
Result: Manual - Operator Dependent
Audit: Review user access to the cluster and ensure that users are not making use of Kubernetes client certificate authentication.
Remediation: Alternative mechanisms provided by Kubernetes such as the use of OIDC should be implemented in place of client certificates.
3.2 Logging
3.2.1
Ensure that a minimal audit policy is created (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --audit-policy-file is set. Review the contents of the file specified and ensure that it contains a valid audit policy.
Remediation: Create an audit policy file for your cluster.
3.2.2
Ensure that the audit policy covers key security concerns (Manual)
Result: Manual - Operator Dependent
Remediation:
4 Worker Node Security Configuration
4.1 Worker Node Configuration Files
4.1.1
Ensure that the kubelet service file permissions are set to 644 or more restrictive (Automated)
Result: Not Applicable
Remediation: RKE2 doesn’t launch the kubelet as a service. It is launched and managed by the RKE2 supervisor process. All configuration is passed to it as command line arguments at run time.
4.1.2
Ensure that the kubelet service file ownership is set to root:root (Automated)
Result: Not Applicable
Remediation: RKE2 doesn’t launch the kubelet as a service. It is launched and managed by the RKE2 supervisor process. All configuration is passed to it as command line arguments at run time.
4.1.3
Ensure that the proxy kubeconfig file permissions are set to 644 or more restrictive (Manual)
Result: Pass
Audit: Run the below command on the worker node.
Verify that if a file is specified and it exists, the permissions are 644 or more restrictive.
Remediation: By default, RKE2 creates rke2-kube-proxy.yaml with 644 permissions. No manual remediation needed.
4.1.4
Ensure that the proxy kubeconfig file ownership is set to root:root (Manual)
Result: Pass
Audit: Run the below command on the master node.
Verify that if a file is specified and it exists, the permissions are 644 or more restrictive.
Remediation: By default, RKE2 creates rke2-kube-proxy.yaml with root:root ownership. No manual remediation needed.
4.1.5
Ensure that the kubelet.conf file permissions are set to 644 or more restrictive (Automated)
Result: Not Applicable
Audit: Run the below command on the worker node.
Remediation: By default, RKE2 creates kubelet.kubeconfig with 644 permissions. No manual remediation needed.
4.1.6
Ensure that the kubelet.conf file ownership is set to root:root (Manual)
Result: Not Applicable
Audit: Run the below command on the master node.
Remediation: By default, RKE2 creates kubelet.kubeconfig with root:root ownership. No manual remediation needed.
4.1.7
Ensure that the certificate authorities file permissions are set to 644 or more restrictive (Manual)
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
Verify that the permissions are 644.
Remediation: By default, RKE2 creates /var/lib/rancher/rke2/server/tls/server-ca.crt with 644 permissions.
4.1.8
Ensure that the client certificate authorities file ownership is set to root:root (Automated)
Result: Pass
Audit: Run the below command on the master node.
Remediation: By default, RKE2 creates /var/lib/rancher/rke2/server/tls/client-ca.crt with root:root ownership.
4.1.9
Ensure that the kubelet configuration file has permissions set to 600 or more restrictive (Automated)
Result: Not Applicable
Remediation: RKE2 doesn’t require or maintain a configuration file for the kubelet process. All configuration is passed to it as command line arguments at run time.
4.1.10
Ensure that the kubelet configuration file ownership is set to root:root (Automated)
Result: Not Applicable
Remediation: RKE2 doesn’t require or maintain a configuration file for the kubelet process. All configuration is passed to it as command line arguments at run time.
4.2 Kubelet
This section contains recommendations for kubelet configuration.
4.2.1
Ensure that the --anonymous-auth argument is set to false (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the value for --anonymous-auth is false.
Remediation: By default, RKE2 starts kubelet with --anonymous-auth set to false. No manual remediation needed.
4.2.2
Ensure that the --authorization-mode argument is not set to AlwaysAllow (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that AlwaysAllow is not present.
Remediation: RKE2 starts kubelet with Webhook as the value for the --authorization-mode argument. No manual remediation needed.
4.2.3
Ensure that the --client-ca-file argument is set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --client-ca-file argument has a ca file associated.
Remediation: By default, RKE2 starts the kubelet process with the --client-ca-file. No manual remediation needed.
4.2.4
Ensure that the --read-only-port argument is set to 0 (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the --read-only-port argument is set to 0.
Remediation: By default, RKE2 starts the kubelet process with the --read-only-port argument set to 0.
4.2.5
Ensure that the --streaming-connection-idle-timeout argument is not set to 0 (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that there's nothing returned.
Remediation: By default, RKE2 does not set --streaming-connection-idle-timeout when starting kubelet.
4.2.6
Ensure that the --protect-kernel-defaults argument is set to true (Automated)
Result: Pass
Audit: Run the below command on the master node.
Remediation: When running with the profile flag set to cis-1.23, RKE2 starts the kubelet process with the --protect-kernel-defaults argument set to true.
4.2.7
Ensure that the --make-iptables-util-chains argument is set to true (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify there are no results returned.
Remediation: By default, RKE2 does not set the --make-iptables-util-chains argument. No manual remediation needed.
4.2.8
Ensure that the --hostname-override argument is not set (Manual)
Result: Not Applicable
Remediation: RKE2 does set this parameter for each host, but RKE2 also manages all certificates in the cluster. It ensures the hostname-override is included as a subject alternative name (SAN) in the kubelet's certificate.
4.2.9
Ensure that the --event-qps argument is set to 0 or a level which ensures appropriate event capture (Manual)
Result: Manual - Operator Dependent
Remediation: See CIS Benchmark guide for further details on configuring this.
4.2.10
Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify the --tls-cert-file and --tls-private-key-file arguments are present and set appropriately.
Remediation: By default, RKE2 sets the --tls-cert-file and --tls-private-key-file arguments when executing the kubelet process.
4.2.11
Ensure that the --rotate-certificates argument is not set to false (Manual)
Result: Pass
Audit: Run the below command on the master node.
Remediation: By default, RKE2 implements it's own logic for certificate generation and rotation.
4.2.12
Ensure that the RotateKubeletServerCertificate argument is set to true (Manual)
Result: Pass
Audit: Run the below command on the master node.
Remediation: By default, RKE2 implements it's own logic for certificate generation and rotation.
4.2.13
Ensure that the Kubelet only makes use of Strong Cryptographic Ciphers (Manual)
Result: Manual - Operator Dependent
Remediation: Configuration of the parameter is dependent on your use case. Please see the CIS Kubernetes Benchmark for suggestions on configuring this for your use case.
5 Kubernetes Policies
5.1 RBAC and Service Accounts
5.1.1
Ensure that the cluster-admin role is only used where required (Manual)
Result: Pass
Remediation: RKE2 does not make inappropriate use of the cluster-admin role. Operators must audit their workloads of additional usage. See the CIS Benchmark guide for more details.
5.1.2
Minimize access to secrets (Manual)
Result: Manual - Operator Dependent
Remediation: RKE2 limits its use of secrets for the system components appropriately, but operators must audit the use of secrets by their workloads. See the CIS Benchmark guide for more details.
5.1.3
Minimize wildcard use in Roles and ClusterRoles (Manual)
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
Verify that there are not wildcards in use.
Remediation: Operators should review their workloads for proper role usage. See the CIS Benchmark guide for more details.
5.1.4
Minimize access to create pods (Manual)
Result: Manual - Operator Dependent
Remediation: Operators should review who has access to create pods in their cluster. See the CIS Benchmark guide for more details.
5.1.5
Ensure that default service accounts are not actively used. (Automated)
Result: Pass.
Audit: For each namespace in the cluster, review the rights assigned to the default service account and ensure that it has no roles or cluster roles bound to it apart from the defaults. Additionally ensure that the automountServiceAccountToken: false setting is in place for each default service account.
Remediation: Create explicit service accounts wherever a Kubernetes workload requires specific access to the Kubernetes API server. Modify the configuration of each default service account to include this value
5.1.6
Ensure that Service Account Tokens are only mounted where necessary (Manual)
Result: Manual - Operator Dependent
Remediation: The pods launched by RKE2 are part of the control plane and generally need access to communicate with the API server, thus this control does not apply to them. Operators should review their workloads and take steps to modify the definition of pods and service accounts which do not need to mount service account tokens to disable it.
5.1.7
Avoid use of system:masters group (Manual)
Result: Manual - Operator Dependent
Remediation: Remove the system:masters group from all users in the cluster.
5.1.7
Limit use of the Bind, Impersonate and Escalate permissions in the Kubernetes cluster (Manual)
Result: Manual - Operator Dependent
Remediation: Where possible, remove the impersonate, bind and escalate rights from subjects.
5.2 Pod Security Standards
5.2.1
Ensure that the cluster has at least one active policy control mechanism in place (Manual)
Result: Manual - Operator Dependent
Remediation: PSA is enabled since v1.23 by default in RKE2, no remediation necessary.
5.2.2
Minimize the admission of privileged containers (Manual)
Result: Pass
Audit: Run the below command on the master node to ensure restricted level is enabled in the config file.
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of privileged containers.
5.2.3
Minimize the admission of containers wishing to share the host process ID namespace (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of privileged containers.
5.2.4
Minimize the admission of containers wishing to share the host IPC namespace (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of privileged containers.
5.2.5
Minimize the admission of containers wishing to share the host network namespace (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of hostNetwork containers.
5.2.6
Minimize the admission of containers with allowPrivilegeEscalation (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of containers with .spec.allowPrivilegeEscalationset to true.
5.2.7
Minimize the admission of root containers (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the returned value is enforce: restricted
Remediation: Create a policy for each namespace in the cluster, ensuring that either MustRunAsNonRoot or MustRunAs with the range of UIDs not including 0, is set.
5.2.8
Minimize the admission of containers with the NET_RAW capability (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that the returned value is enforce: restricted.
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of containers with the NET_RAW capability.
5.2.9
Minimize the admission of containers with added capabilities (Automated)
Result: Manual
Remediation: Ensure that allowedCapabilities is not present in policies for the cluster unless it is set to an empty array.
5.2.10
Minimize the admission of containers with capabilities assigned (Manual)
Result: Manual
Remediation: Review the use of capabilities in applications running on your cluster. Where a namespace contains applications which do not require any Linux capabilities to operate consider adding a PSP which forbids the admission of containers which do not drop all capabilities.
5.2.11
Minimize the admission of Windows HostProcess containers (Manual)
Result: Manual
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of containers that have .securityContext.windowsOptions.hostProcess set to true.
5.2.12
Minimize the admission of HostPath volumes (Manual)
Result: Manual
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of containers with hostPath volumes.
5.2.13
Minimize the admission of containers which use HostPorts (Manual)
Result: Manual
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of containers which use hostPort sections.
5.3 Network Policies and CNI
5.3.1
Ensure that the CNI in use supports Network Policies (Automated)
Result: Pass
Audit: Review the documentation of CNI plugin in use by the cluster, and confirm that it supports Ingress and Egress network policies.
Remediation: By default, RKE2 use Canal (Calico and Flannel) and fully supports network policies.
5.3.2
Ensure that all Namespaces have Network Policies defined (Automated)
Result: Pass
Audit: Run the below command on the master node.
Verify that there are network policies applied to each of the namespaces.
Remediation: RKE2, when executed with the --profile=cis-1.23 argument applies a secure network policy that only allows intra-namespace traffic and DNS to kube-system. No manual remediation needed.
5.4 Secrets Management
5.4.1
Prefer using secrets as files over secrets as environment variables (Manual)
Result: Manual
Audit: Run the following command to find references to objects which use environment variables defined from secrets.
Remediation: If possible, rewrite application code to read secrets from mounted secret files, rather than from environment variables.
5.4.2
Consider external secret storage (Manual)
Result: Manual
Audit: Review your secrets management implementation.
Remediation: Refer to the secrets management options offered by your cloud provider or a third-party secrets management solution.
5.5 Extensible Admission Control
5.5.1
Configure Image Provenance using ImagePolicyWebhook admission controller (Manual)
Result: Manual
Audit: Review the pod definitions in your cluster and verify that image provenance is configured as appropriate.
Remediation: Follow the Kubernetes documentation and setup image provenance.
5.6 Omitted
The v1.23 guide skips 5.6 and goes from 5.5 to 5.7. We are including it here merely for explanation.
5.7 General Policies
These policies relate to general cluster management topics, like namespace best practices and policies applied to pod objects in the cluster.
5.7.1
Create administrative boundaries between resources using namespaces (Manual)
Result: Manual
Audit: Run the below command and review the namespaces created in the cluster.
Ensure that these namespaces are the ones you need and are adequately administered as per your requirements.
Remediation: Follow the documentation and create namespaces for objects in your deployment as you need them.
5.7.2
Ensure that the seccomp profile is set to docker/default in your pod definitions (Manual)
Result: Manual
Audit: Review the pod definitions in your cluster. It should create a line as below:
Remediation: Review the Kubernetes documentation and if needed, apply a relevant PodSecurityPolicy.
5.7.3
Apply Security Context to Your Pods and Containers (Manual)
Result: Manual
Audit: Review the pod definitions in your cluster and verify that you have security contexts defined as appropriate.
Remediation: Follow the Kubernetes documentation and apply security contexts to your pods. For a suggested list of security contexts, you may refer to the CIS Security Benchmark.
5.7.4
The default namespace should not be used (Manual)
Result: Manual
Audit: Run the below command on the master node.
Verify that there are no resources applied to the default namespace.
Remediation: By default, RKE2 does not utilize the default namespace.
FIPS 140-2 is a U.S. Federal Government security standard used to approve cryptographic modules. This document explains how RKE2 is built with FIPS validated cryptographic libraries.
Use of FIPS Compatible Go compiler.
The Go compiler in use can be found here. Each component of the system is built with the version of this compiler that matches the same standard Go compiler version that would be used otherwise.
This version of Go replaces the standard Go crypto libraries with the FIPS validated BoringCrypto module. See GoBoring's readme for more details. This module was originally validated by NIST as the Rancher Kubernetes Cryptographic Library in order to ensure support on a wider range of systems. However, due to changes introduced by SP 800-56A Rev3, this validation is now historical. A re-validation effort is currently underway to return this module to active FIPS 140-2 status.
FIPS Support in Cluster Components
Most of the components of the RKE2 system are statically compiled with the GoBoring Go compiler implementation. RKE2, from a component perspective, is broken up in a number of sections. The list below contains the sections and associated components.
Kubernetes
API Server
Controller Manager
Scheduler
Kubelet
Kube Proxy
Metric Server
Kubectl
Helm Charts
Flannel
Calico
CoreDNS
Runtime
To ensure that all aspects of the system architecture are using FIPS 140-2 compliant algorithm implementations, the RKE2 runtime contains utilities statically compiled with the FIPS enabled Go compiler for FIPS 140-2 compliance. This ensures that all levels of the stack are compliant from Kubernetes daemons to container orchestration mechanics.
etcd
containerd
containerd-shim
containerd-shim-runc-v1
containerd-shim-runc-v2
ctr
crictl
runc
CNI
As of v1.21.2, RKE2 supports selecting a different CNI via the --cni flag and comes bundled with several CNIs including Canal (default), Calico, Cilium, and Multus. Of these, only Canal (the default) is rebuilt for FIPS compliance.
Ingress
RKE2 ships with NGINX as its default ingress provider. As of v1.21+, this component is FIPS compliant. There are two primary sub-components for NGINX ingress:
controller - responsible for monitoring/updating Kubernetes resources and configuring the server accordingly
server - responsible for accepting and routing traffic
The controller is written in Go and as such is compiled using our FIPS compatible Go compiler.
The server is written in C and also requires OpenSSL to function properly. As such, it leverages a FIPS-validated version of OpenSSL to achieve FIPS compliance.
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