KSPM — Kubernetes® Security Posture ManagementKSPM — Kubernetes® Security Posture Management

Rules for checking Kubernetes cluster configuration.

Restrictive permissions for Kubelet service file are setRestrictive permissions for Kubelet service file are set

DescriptionDescription

The kubelet service file controls various parameters that set the behavior of the kubelet service in the worker node.
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.

RecommendationsRecommendations

To perform the audit manually:

Run the below command (based on the file location on your system) on the each worker node.
For example:

stat -c %a /etc/systemd/system/kubelet.service.d/kubeadm.conf

Verify that the permissions are set as 600 or more restrictive.

Remediation:

Run the below command (based on the file location on your system) on the each worker node.
For example:

chmod 600 /etc/systemd/system/kubelet.service.d/kubeadm.conf

Kubelet service file ownership is set to root:rootKubelet service file ownership is set to root:root

DescriptionDescription

The kubelet service file controls various parameters that set the behavior of the kubelet service in the worker node.
You should set its file ownership to maintain the integrity of the file.
The file should be owned by root:root.

RecommendationsRecommendations

To perform the audit manually:

Run the below command (based on the file location on your system) on the each worker node.
For example:

stat -c %U:%G /etc/systemd/system/kubelet.service.d/kubeadm.conf

Verify that the ownership is set to root:root.

Remediation:

Run the below command (based on the file location on your system) on the each worker node.
For example:

chown root:root /etc/systemd/system/kubelet.service.d/kubeadm.conf

Restrictive permissions for kubeconfig configuration file are setRestrictive permissions for kubeconfig configuration file are set

DescriptionDescription

The kubelet.conf file is the kubeconfig file for the node. It controls various parameters that set the behavior and identity of the worker node.
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.

RecommendationsRecommendations

To perform the audit manually:

Run the below command (based on the file location on your system) on the each worker node.
For example:

stat -c %a /etc/kubernetes/kubelet.conf

Verify that the permissions are 600 or more restrictive.

Remediation:

Run the below command (based on the file location on your system) on the each worker node.
For example:

chmod 600 /etc/kubernetes/kubelet.conf

The owner of kubeconfig configuration file is set to root:rootThe owner of kubeconfig configuration file is set to root:root

DescriptionDescription

The kubelet.conf file is the kubeconfig file for the node. It controls various parameters that set the behavior and identity of the worker node.
You should set its file ownership to maintain the integrity of the file.
The file should be owned by root:root.

RecommendationsRecommendations

To perform the audit manually:

Run the below command (based on the file location on your system) on the each worker node.
For example:

stat -c %U:%G /etc/kubernetes/kubelet.conf

Verify that the ownership is set to root:root.

Remediation:

Run the below command (based on the file location on your system) on the each worker node.
For example:

chown root:root /etc/kubernetes/kubelet.conf

Restrictive permissions for Kubelet configuration file are setRestrictive permissions for Kubelet configuration file are set

DescriptionDescription

Ensure that if the kubelet refers to a configuration file with the --config argument, that file has permissions of 600 or more restrictive.
The kubelet reads various parameters, including security settings, from a config file specified by the --config argument.
If this file is specified, 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.

RecommendationsRecommendations

To perform the audit manually:

Run the below command (based on the file location on your system) on the each worker node.
For example:

stat -c %a /var/lib/kubelet/config.yaml

Verify that the permissions are set as 600 or more restrictive.

Remediation:

Run the following command (using the config file location identified in the Audit step):

chmod 600 /var/lib/kubelet/config.yaml

The owner of Kubelet configuration file is set to root:rootThe owner of Kubelet configuration file is set to root:root

DescriptionDescription

Ensure that if the kubelet refers to a configuration file with the --config argument, that file is owned by root:root.
The kubelet reads various parameters, including security settings, from a config file specified by the --config argument.
If this file is specified, you should restrict its file permissions to maintain the integrity of the file.
The file should be owned by root:root.

RecommendationsRecommendations

To perform the audit manually:

Run the below command (based on the file location on your system) on the each worker node.
For example:

stat -c %U:%G /var/lib/kubelet/config.yaml

Verify that the ownership is set to root:root.

Remediation:

Run the following command (using the config file location identied in the Audit step):

chown root:root /etc/kubernetes/kubelet.conf

Requests from anonymous users to Kubelet server are disabledRequests from anonymous users to Kubelet server are disabled

DescriptionDescription

Disable anonymous requests to the Kubelet server.
When enabled, requests that are not rejected by other configured authentication methods are treated as anonymous requests.
These requests are then served by the Kubelet server.
You should rely on authentication to authorize access and disallow anonymous requests.

RecommendationsRecommendations

To perform the audit manually:

If using a Kubelet configuration file, check that there is an entry for authentication: anonymous: enabled set to false.
Run the following command on each node:

ps -ef | grep kubelet

Verify that the --anonymous-auth argument is set to false.
This executable argument may be omitted, provided there is a corresponding entry set to false in the Kubelet config file.

Remediation:

If using a Kubelet config file, edit the file to set authentication: anonymous: enabled to false.
If using executable arguments, edit the kubelet service file /etc/kubernetes/kubelet.conf on each worker node and set the below parameter in KUBELET_SYSTEM_PODS_ARGS variable:
--anonymous-auth=false
Based on your system, restart the kubelet service. For example:

systemctl daemon-reload
systemctl restart kubelet.service

Only explicitly authorized requests to Kubelet server are allowedOnly explicitly authorized requests to Kubelet server are allowed

DescriptionDescription

Do not allow all requests. Enable explicit authorization.
Kubelets, by default, allow all authenticated requests (even anonymous ones) without needing explicit authorization checks from the apiserver.
You should restrict this behavior and only allow explicitly authorized requests.

RecommendationsRecommendations

To perform the audit manually:

Run the following command on each node:

ps -ef | grep kubelet

If the --authorization-mode argument is present, check that it is not set to AlwaysAllow.
If it is not present, check that there is a Kubelet config file specified by --config, and that file sets authorization: mode to something other than AlwaysAllow.
It is also possible to review the running configuration of a Kubelet via the /configz endpoint on the Kubelet API port (typically 10250/TCP).
Accessing these with appropriate credentials will provide details of the Kubelet's configuration.

Remediation:

If using a Kubelet config file, edit the file to set authorization: mode to Webhook.
If using executable arguments, edit the kubelet service file /etc/kubernetes/kubelet.conf on each worker node and set the below parameter in KUBELET_AUTHZ_ARGS variable:
--authorization-mode=Webhook
Based on your system, restart the kubelet service.
For example:

systemctl daemon-reload
systemctl restart kubelet.service

Kubelet authentication via certificates is enabledKubelet authentication via certificates is enabled

DescriptionDescription

Enable Kubelet authentication using certificates.
The connections from the apiserver to the kubelet are used for fetching logs for pods, attaching (through kubectl) to running pods, and using the kubelet's port-forwarding functionality.
These connections terminate at the kubelet's HTTPS endpoint.
By default, the apiserver does not verify the kubelet's serving certificate, which makes the connection subject to man-in-the-middle attacks, and unsafe to run over untrusted and/or public networks.
Enabling Kubelet certificate authentication ensures that the apiserver could authenticate the Kubelet before submitting any requests.

RecommendationsRecommendations

To perform the audit manually:

Run the following command on each node:

ps -ef | grep kubelet

Verify that the --client-ca-file argument exists and is set to the location of the client certificate authority file.
If the --client-ca-file argument is not present, check that there is a Kubelet config file specified by --config, and that the file sets authentication: x509: clientCAFile to the location of the client certificate authority file.

Remediation:

If using a Kubelet config file, edit the file to set authentication: x509: clientCAFile to the location of the client CA file.
If using command line arguments, edit the kubelet service file /etc/kubernetes/kubelet.conf on each worker node and set the below parameter in KUBELET_AUTHZ_ARGS variable:
--client-ca-file=<path/to/client-ca-file>
Based on your system, restart the kubelet service.
For example:

systemctl daemon-reload
systemctl restart kubelet.service

Kubelet is allowed to manage iptablesKubelet is allowed to manage iptables

DescriptionDescription

Allow Kubelet to manage iptables.
Kubelets can automatically manage the required changes to iptables based on how you choose your networking options for the pods.
It is recommended to let kubelets manage the changes to iptables.
This ensures that the iptables configuration remains in sync with pods networking configuration.
Manually configuring iptables with dynamic pod network configuration changes might hamper the communication between pods/containers and to the outside world.
You might have iptables rules too restrictive or too open.

RecommendationsRecommendations

To perform the audit manually:

Run the following command on each node:

ps -ef | grep kubelet

Verify that if the --make-iptables-util-chains argument exists, then it is set to true.
If the --make-iptables-util-chains argument does not exist, and there is a Kubelet config file specified by --config, verify that the file does not set makeIPTablesUtilChains to false.

Remediation:

If using a Kubelet config file, edit the file to set makeIPTablesUtilChains: true.
If using command line arguments, edit the kubelet service file /etc/kubernetes/kubelet.conf on each worker node and remove the --make-iptables-util-chains argument from the KUBELET_SYSTEM_PODS_ARGS variable.
Based on your system, restart the kubelet service.
For example:

systemctl daemon-reload
systemctl restart kubelet.service

Kubelet client certificate rotation is enabledKubelet client certificate rotation is enabled

DescriptionDescription

Enable kubelet client certificate rotation.
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 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 requires the RotateKubeletClientCertificate feature gate to be enabled (which is the default since Kubernetes v1.7)

RecommendationsRecommendations

To perform the audit manually:

Run the following command on each node:

ps -ef | grep kubelet

Verify that the RotateKubeletServerCertificate argument is not present, or is set to true.
If the RotateKubeletServerCertificate argument is not present, verify that if there is a Kubelet config file specified by --config, that file does not contain RotateKubeletServerCertificate: false.

Remediation:

If using a Kubelet config file, edit the file to add the line rotateCertificates: true or remove it altogether to use the default value.
If using command line arguments, edit the kubelet service file /etc/kubernetes/kubelet.conf on each worker node and remove --rotate-certificates=false argument from the KUBELET_CERTIFICATE_ARGS variable or set --rotate-certificates=true.
Based on your system, restart the kubelet service.
For example:

systemctl daemon-reload
systemctl restart kubelet.service