V-242399

Discussion

Kubernetes allows a user to configure kubelets with dynamic configurations. When dynamic configuration is used, the kubelet will watch for changes to the configuration file. When changes are made, the kubelet will automatically restart. Allowing this capability bypasses access restrictions and authorizations. Using this capability, an attacker can lower the security posture of the kubelet, which includes allowing the ability to run arbitrary commands in any container running on that node.

Check Content

This check is only applicable for Kubernetes versions 1.25 and older.  

On the Control Plane, change to the manifests' directory at /etc/kubernetes/manifests and run the command:
grep -i feature-gates *

In each manifest file, if the feature-gates does not exist, or does not contain the "DynamicKubeletConfig" flag, or sets the flag to "true", this is a finding.

On each Control Plane and Worker node, run the command:
ps -ef | grep kubelet

Verify the "feature-gates" option is not present.

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

Inspect the content of the config file:
If the "featureGates" setting is not present, or does not contain the "DynamicKubeletConfig", or sets the flag to "true", this is a finding.