CIS 1.23 Self-Assessment Guide
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)
Rationale
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/agent/pod-manifests/kube-apiserver.yaml
644
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)
Rationale
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/agent/pod-manifests/kube-apiserver.yaml
root:root
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)
Rationale
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/agent/pod-manifests/kube-controller-manager.yaml
644
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)
Rationale
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/agent/pod-manifests/kube-controller-manager.yaml
root:root
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)
Rationale
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/agent/pod-manifests/kube-scheduler.yaml
644
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)
Rationale
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/agent/pod-manifests/kube-scheduler.yaml
root:root
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)
Rationale
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/agent/pod-manifests/etcd.yaml
644
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)
Rationale
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/agent/pod-manifests/etcd.yaml
root:root
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)
Rationale
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/server/manifests/rke2-canal.yml
644
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)
Rationale
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/server/manifests/rke2-canal.yml
root:root
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)
Rationale
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/server/db/etcd
700
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)
Rationale
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/server/db/etcd
etcd:etcd
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)
Rationale
In RKE2, this file is located at /var/lib/rancher/rke2/server/cred/admin.kubeconfig
.
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/server/cred/admin.kubeconfig
644
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)
Rationale
In RKE2, this file is located at /var/lib/rancher/rke2/server/cred/admin.kubeconfig
.
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/server/cred/admin.kubeconfig
root:root
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)
Rationale
The scheduler.conf file is the kubeconfig file for the Scheduler. You should restrict its file permissions to maintain the integrity of the file. The file should be writable by only the administrators on the system.
In RKE2, this file is located at /var/lib/rancher/rke2/server/cred/scheduler.kubeconfig
.
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/server/cred/scheduler.kubeconfig
644
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)
Rationale
In RKE2, this file is located at /var/lib/rancher/rke2/server/cred/scheduler.kubeconfig
.
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/server/cred/scheduler.kubeconfig
root:root
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)
Rationale
In RKE2, this file is located at /var/lib/rancher/rke2/server/cred/controller.kubeconfig
.
Result: Pass
Audit:
stat -c %a /var/lib/rancher/rke2/server/cred/controller.kubeconfig
644
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)
Rationale
In RKE2, this file is located at /var/lib/rancher/rke2/server/cred/controller.kubeconfig
.
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/server/cred/controller.kubeconfig
root:root
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)
Rationale
Result: Pass
Audit:
stat -c %U:%G /var/lib/rancher/rke2/server/tls
root:root
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
stat -c %n\ %a /var/lib/rancher/rke2/server/tls/*.crt
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
stat -c %n\ %a /var/lib/rancher/rke2/server/tls/*.key
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)
Rationale
If you are using RBAC authorization, it is generally considered reasonable to allow anonymous access to the API Server for health checks and discovery purposes, and hence this recommendation is Manual. However, you should consider whether anonymous discovery is an acceptable risk for your purposes.
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Most users do not need this feature at all, and cluster admins should consider disabling it. Clusters that do need to use this feature should consider using some custom policy to manage usage of it.
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Note: This is an Alpha feature in the Kubernetes 1.15 release.
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
The AlwaysAdmit admission controller was deprecated in Kubernetes v1.13. Its behavior was equivalent to turning off all admission controllers.
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
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.
grep aescbc /var/lib/rancher/rke2/server/cred/encryption-config.json
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)
Rationale
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-controller-manager | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-controller-manager | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-controller-manager | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-controller-manager | grep -v grep
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)
Rationale
Providing the root certificate for the API server's serving certificate to the controller manager with the --root-ca-file
argument allows the controller manager to inject the trusted bundle into pods so that they can verify TLS connections to the API server.
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-controller-manager | grep -v grep
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)
Rationale
Note: This recommendation only applies if you let kubelets get their certificates from the API server. In case your kubelet certificates come from an outside authority/tool (e.g. Vault) then you need to take care of rotation yourself.
Result: Not Applicable
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-controller-manager | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-controller-manager | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-scheduler | grep -v grep
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)
Rationale
The Scheduler API service which runs on port 10251/TCP by default is used for health and metrics information and is available without authentication or encryption. As such it should only be bound to a localhost interface, to minimize the cluster's attack surface.
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-scheduler | grep -v grep
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)
Rationale
Result: Not Applicable
Audit: Run the below command on the master node.
grep -E 'cert-file|key-file' /var/lib/rancher/rke2/server/db/etcd/config
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)
Rationale
Result: Not Applicable
Audit: Run the below command on the master node.
grep 'client-cert-auth' /var/lib/rancher/rke2/server/db/etcd/config
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
grep 'auto-tls' /var/lib/rancher/rke2/server/db/etcd/config
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)
Rationale
Result: Not Applicable
Audit: Run the below command on the master node.
grep -E 'peer-server-client.crt|peer-server-client.key' /var/lib/rancher/rke2/server/db/etcd/config
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)
Rationale
Result: Not Applicable
Audit: Run the below command on the master node.
grep 'peer-client-cert-auth' /var/lib/rancher/rke2/server/db/etcd/config
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
grep 'peer-auto-tls' /var/lib/rancher/rke2/server/db/etcd/config
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)
Rationale
Authentication to etcd is based on whether the certificate presented was issued by a trusted certificate authority. There is no checking of certificate attributes such as common name or subject alternative name. As such, if any attackers were able to gain access to any certificate issued by the trusted certificate authority, they would be able to gain full access to the etcd database.
Result: Pass
Audit: Run the below command on the master node.
# To find the ca file used by etcd:
grep 'trusted-ca-file' /var/lib/rancher/rke2/server/db/etcd/config
# To find the kube-apiserver process:
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kube-apiserver | grep -v grep
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)
Rationale
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)
Rationale
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)
Rationale
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)
Rationale
It is possible to run kube-proxy
with the kubeconfig parameters configured as a Kubernetes ConfigMap instead of a file. In this case, there is no proxy kubeconfig file.
Result: Pass
Audit: Run the below command on the worker node.
stat -c %a /var/lib/rancher/rke2/server/manifests/rke2-kube-proxy.yaml
644
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
stat -c %U:%G /var/lib/rancher/rke2/server/manifests/rke2-kube-proxy.yaml
root:root
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)
Rationale
Result: Not Applicable
Audit: Run the below command on the worker node.
stat -c %a /var/lib/rancher/rke2/agent/kubelet.kubeconfig
644
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)
Rationale
Result: Not Applicable
Audit: Run the below command on the master node.
stat -c %U:%G /var/lib/rancher/rke2/agent/kubelet.kubeconfig
root:root
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)
Rationale
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
stat -c %a /var/lib/rancher/rke2/server/tls/server-ca.crt
644
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
stat -c %U:%G /var/lib/rancher/rke2/server/tls/client-ca.crt
root:root
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)
Rationale
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)
Rationale
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
Note: By default, --streaming-connection-idle-timeout
is set to 4 hours which might be too high for your environment. Setting this as appropriate would additionally ensure that such streaming connections are timed out after serving legitimate use cases.
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
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)
Rationale
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)
Rationale
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
The --rotate-certificates
setting causes the kubelet to rotate its client certificates by creating new CSRs as its existing credentials expire. This automated periodic rotation ensures that the there is no downtime due to expired certificates and thus addressing availability in the CIA security triad.
Note: This recommendation only applies if you let kubelets get their certificates from the API server. In case your kubelet certificates come from an outside authority/tool (e.g. Vault) then you need to take care of rotation yourself.
Note:This feature also require the RotateKubeletClientCertificate
feature gate to be enabled (which is the default since Kubernetes v1.7)
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
Note: This recommendation only applies if you let kubelets get their certificates from the API server. In case your kubelet certificates come from an outside authority/tool (e.g. Vault) then you need to take care of rotation yourself.
Result: Pass
Audit: Run the below command on the master node.
/bin/ps -ef | grep kubelet | grep -v grep
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)
Rationale
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)
Rationale
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)
Rationale
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)
Rationale
Result: Manual - Operator Dependent
Audit: Run the below command on the master node.
# Retrieve the roles defined across each namespaces in the cluster and review for wildcards
/var/lib/rancher/rke2/bin/kubectl get roles --all-namespaces -o yaml
# Retrieve the cluster roles defined in the cluster and review for wildcards
/var/lib/rancher/rke2/bin/kubectl get clusterroles -o yaml
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)
Rationale
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)
Rationale
Where access to the Kubernetes API from a pod is required, a specific service account should be created for that pod, and rights granted to that service account.
The default service account should be configured such that it does not provide a service account token and does not have any explicit rights assignments.
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
automountServiceAccountToken: false
5.1.6
Ensure that Service Account Tokens are only mounted where necessary (Manual)
Rationale
Avoiding mounting these tokens removes this attack avenue.
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)
Rationale
When combined with client certificate authentication, use of this group can allow for irrevocable cluster-admin level credentials to exist for a cluster.
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)
Rationale
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)
Rationale
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)
Rationale
There should be at least one PodSecurityPolicy (PSP) defined which does not permit containers to share the host PID namespace.
If you need to run containers which require hostPID, this should be defined in a separate PSP and you should carefully check RBAC controls to ensure that only limited service accounts and users are given permission to access that PSP.
Result: Pass
Audit: Run the below command on the master node to ensure restricted level is enabled in the config file.
config_file=$(ps aux | grep kube-apiserver | grep -- --admission-control-config-file | sed 's%.*admission-control-config-file[= ]\([^ ]*\).*%\1%')
grep "enforce:" ${config_file}
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of privileged containers.
5.2.3
Minimize the admission of containers wishing to share the host process ID namespace (Automated)
Rationale
There should be at least one admission control policy defined which does not permit containers to share the host PID namespace.
If you need to run containers which require hostPID, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
Result: Pass
Audit: Run the below command on the master node.
config_file=$(ps aux | grep kube-apiserver | grep -- --admission-control-config-file | sed 's%.*admission-control-config-file[= ]\([^ ]*\).*%\1%')
grep "enforce:" ${config_file}
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of privileged containers.
5.2.4
Minimize the admission of containers wishing to share the host IPC namespace (Automated)
Rationale
There should be at least one admission control policy defined which does not permit containers to share the host IPC namespace.
If you need to run containers which require hostIPC, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
Result: Pass
Audit: Run the below command on the master node.
config_file=$(ps aux | grep kube-apiserver | grep -- --admission-control-config-file | sed 's%.*admission-control-config-file[= ]\([^ ]*\).*%\1%')
grep "enforce:" ${config_file}
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of privileged containers.
5.2.5
Minimize the admission of containers wishing to share the host network namespace (Automated)
Rationale
There should be at least one admission control policy defined which does not permit containers to share the host network namespace.
If you need to run containers which require access to the host's network namespaces, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
Result: Pass
Audit: Run the below command on the master node.
config_file=$(ps aux | grep kube-apiserver | grep -- --admission-control-config-file | sed 's%.*admission-control-config-file[= ]\([^ ]*\).*%\1%')
grep "enforce:" ${config_file}
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of hostNetwork containers.
5.2.6
Minimize the admission of containers with allowPrivilegeEscalation
(Automated)
Rationale
There should be at least one admission control policy defined which does not permit containers to allow privilege escalation. The option exists (and is defaulted to true) to permit setuid binaries to run.
If you have need to run containers which use setuid binaries or require privilege escalation, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
Result: Pass
Audit: Run the below command on the master node.
config_file=$(ps aux | grep kube-apiserver | grep -- --admission-control-config-file | sed 's%.*admission-control-config-file[= ]\([^ ]*\).*%\1%')
grep "enforce:" ${config_file}
Verify that the returned value is enforce: restricted
Remediation: Add policies to each namespace in the cluster which has user workloads to restrict the admission of containers with .spec.allowPrivilegeEscalationset to true.
5.2.7
Minimize the admission of root containers (Automated)
Rationale
Ideally, all containers should run as a defined non-UID 0 user.
There should be at least one admission control policy defined which does not permit root containers.
If you need to run root containers, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
Result: Pass
Audit: Run the below command on the master node.
config_file=$(ps aux | grep kube-apiserver | grep -- --admission-control-config-file | sed 's%.*admission-control-config-file[= ]\([^ ]*\).*%\1%')
grep "enforce:" ${config_file}
Verify that the returned value is enforce: restricted
Remediation:
Create a policy for each namespace in the cluster, ensuring that either MustRunAsNonRoot
or MustRunAs
with the range of UIDs not including 0, is set.
5.2.8
Minimize the admission of containers with the NET_RAW capability (Automated)
Rationale
Ideally, all containers should drop this capability.
There should be at least one admission control policy defined which does not permit containers with the NET_RAW capability.
If you need to run containers with this capability, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
Result: Pass
Audit: Run the below command on the master node.
config_file=$(ps aux | grep kube-apiserver | grep -- --admission-control-config-file | sed 's%.*admission-control-config-file[= ]\([^ ]*\).*%\1%')
grep "enforce:" ${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 containers with the NET_RAW
capability.
5.2.9
Minimize the admission of containers with added capabilities (Automated)
Rationale
There should be at least one policy defined which prevents containers with capabilities beyond the default set from launching.
If you need to run containers with additional capabilities, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
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)
Rationale
In many cases applications running in containers do not require any capabilities to operate, so from the perspective of the principal of least privilege use of capabilities should be minimized.
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)
Rationale
In many cases applications running in containers do not require any capabilities to operate, so from the perspective of the principal of least privilege use of capabilities should be minimized.
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)
Rationale
There should be at least one admission control policy defined which does not permit containers to mount hostPath volumes.
If you need to run containers which require hostPath volumes, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
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)
Rationale
There should be at least one admission control policy defined which does not permit containers which require the use of HostPorts.
If you need to run containers which require HostPorts, this should be defined in a separate policy and you should carefully check to ensure that only limited service accounts and users are given permission to use that policy.
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)
Rationale
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)
Rationale
Network Policies are namespace scoped. When a network policy is introduced to a given namespace, all traffic not allowed by the policy is denied. However, if there are no network policies in a namespace all traffic will be allowed into and out of the pods in that namespace.
Result: Pass
Audit: Run the below command on the master node.
for i in kube-system kube-public default; do
/var/lib/rancher/rke2/bin/kubectl get networkpolicies -n $i;
done
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)
Rationale
Result: Manual
Audit: Run the following command to find references to objects which use environment variables defined from secrets.
/var/lib/rancher/rke2/bin/kubectl get all -o jsonpath='{range .items[?(@..secretKeyRef)]} {.kind} {.metadata.name} {"\n"}{end}' -A
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)
Rationale
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)
Rationale
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)
Rationale
Result: Manual
Audit: Run the below command and review the namespaces created in the cluster.
/var/lib/rancher/rke2/bin/kubectl get namespaces
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)
Rationale
Result: Manual
Audit: Review the pod definitions in your cluster. It should create a line as below:
annotations:
seccomp.security.alpha.kubernetes.io/pod: docker/default
Remediation: Review the Kubernetes documentation and if needed, apply a relevant PodSecurityPolicy.
5.7.3
Apply Security Context to Your Pods and Containers (Manual)
Rationale
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)
Rationale
Result: Manual
Audit: Run the below command on the master node.
/var/lib/rancher/rke2/bin/kubectl get all -n default
Verify that there are no resources applied to the default namespace.
Remediation: By default, RKE2 does not utilize the default namespace.