lacework-global-325
3.2.6 Ensure that the --protect-kernel-defaults argument is set to true (Automated)
Profile Applicability
• Level 1
Description
Protect tuned kernel parameters from overriding kubelet default kernel parameter values.
Rationale
Kernel parameters are usually tuned and hardened by the system administrators before putting the systems into production. These parameters protect the kernel and the system. Your kubelet kernel defaults that rely on such parameters should be appropriately set to match the desired secured system state. Ignoring this could potentially lead to running pods with undesired kernel behavior.
Impact
You would have to re-tune kernel parameters to match kubelet parameters.
Audit
Audit Method 1:
If using a Kubelet configuration file, check that there is an entry for protectKernelDefaults is set to true.
First, SSH to the relevant node:
Run the following command on each node to find the appropriate Kubelet config file:
ps -ef | grep kubelet
The output of the above command should return something similar to --config /etc/kubernetes/kubelet/kubelet-config.json which is the location of the Kubelet config file.
Open the Kubelet config file:
cat /etc/kubernetes/kubelet/kubelet-config.json
Verify that the --protect-kernel-defaults=true.
If the --protect-kernel-defaults argument is not present, check that there is a Kubelet config file specified by --config, and that the file sets protectKernelDefaults to true.
Audit Method 2:
If using the api configz endpoint consider searching for the status of "protectKernelDefaults" by extracting the live configuration from the nodes running kubelet.
Set the local proxy port and the following variables and provide proxy port number and node name;
HOSTNAME_PORT="localhost-and-port-number"
NODE_NAME="The-Name-Of-Node-To-Extract-Configuration" from the output of "kubectl get nodes"
kubectl proxy --port=8001 &
export HOSTNAME_PORT=localhost:8001 (example host and port number)
export NODE_NAME=ip-192.168.31.226.ec2.internal (example node name from "kubectl get nodes")
curl -sSL "http://${HOSTNAME_PORT}/api/v1/nodes/${NODE_NAME}/proxy/configz"
Remediation
Remediation Method 1:
If modifying the Kubelet config file, edit the kubelet-config.json file /etc/kubernetes/kubelet/kubelet-config.json and set the protectKernelDefaults parameter to true.
Remediation Method 2:
If using executable arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubelet-args.conf on each worker node and add the below parameter at the end of the KUBELET_ARGS variable string:
----protect-kernel-defaults=true
Remediation Method 3:
If using the api configz endpoint consider searching for the status of "protectKernelDefaults": by extracting the live configuration from the nodes running kubelet.
**See detailed step-by-step configmap procedures in Reconfigure a Node's Kubelet in a Live Cluster, and then rerun the curl statement from audit process to check for kubelet configuration changes
kubectl proxy --port=8001 &
export HOSTNAME_PORT=localhost:8001 (example host and port number)
export NODE_NAME=ip-192.168.31.226.ec2.internal (example node name from "kubectl get nodes")
curl -sSL "http://${HOSTNAME_PORT}/api/v1/nodes/${NODE_NAME}/proxy/configz"
For all three remediations: Based on the node's service manager (the example below is for systemctl), restart the kubelet service and check status:
systemctl daemon-reload
systemctl restart kubelet.service
systemctl status kubelet -l