Kubernetes Kubelet must enable tlsPrivateKeyFile for client authentication to secure service.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-242424	CNTR-K8-001460	SV-242424r961110_rule		Medium

Description
Kubernetes container and pod configuration are maintained by Kubelet. Kubelet agents register nodes with the API Server, mount volume storage, and perform health checks for containers and pods. Anyone who gains access to Kubelet agents can effectively control applications within the pods and containers. Using authenticity protection, the communication can be protected against man-in-the-middle attacks/session hijacking and the insertion of false information into sessions. The communication session is protected by utilizing transport encryption protocols such as TLS. TLS provides the Kubernetes API Server with a means to authenticate sessions and encrypt traffic. To enable encrypted communication for Kubelet, the tlsPrivateKeyFile must be set. This parameter gives the location of the SSL Certificate Authority file used to secure Kubelet communication.

Description

Kubernetes container and pod configuration are maintained by Kubelet. Kubelet agents register nodes with the API Server, mount volume storage, and perform health checks for containers and pods. Anyone who gains access to Kubelet agents can effectively control applications within the pods and containers. Using authenticity protection, the communication can be protected against man-in-the-middle attacks/session hijacking and the insertion of false information into sessions. The communication session is protected by utilizing transport encryption protocols such as TLS. TLS provides the Kubernetes API Server with a means to authenticate sessions and encrypt traffic. To enable encrypted communication for Kubelet, the tlsPrivateKeyFile must be set. This parameter gives the location of the SSL Certificate Authority file used to secure Kubelet communication.

STIG	Date
Kubernetes Security Technical Implementation Guide	2024-06-10

Details

Check Text ( C-45699r918180_chk )
On the Control Plane, run the command: ps -ef \| grep kubelet If the "--tls-private-key-file" option exists, this is a finding. Note the path to the config file (identified by --config). Run the command: grep -i tlsPrivateKeyFile If the setting "tlsPrivateKeyFile" is not set or contains no value, this is a finding.

Fix Text (F-45657r918181_fix)
On the Control Plane, run the command: ps -ef \| grep kubelet Remove the "--tls-private-key-file" option if present. Note the path to the config file (identified by --config). Edit the Kubernetes Kubelet config file: Set "tlsPrivateKeyFile" to a path containing the appropriate private key. Restart the kubelet service using the following command: systemctl daemon-reload && systemctl restart kubelet

Fix Text (F-45657r918181_fix)

On the Control Plane, run the command:
ps -ef | grep kubelet

Remove the "--tls-private-key-file" option if present.

Note the path to the config file (identified by --config).

Edit the Kubernetes Kubelet config file:
Set "tlsPrivateKeyFile" to a path containing the appropriate private key.

Restart the kubelet service using the following command:
systemctl daemon-reload && systemctl restart kubelet