Cis Oke V180 3.2.7

CIS OKE Benchmark v1.8.0 - Control 3.2.7

Profile Applicability

• Level: 1

Description

Security relevant information should be captured. The --event-qps flag on the Kubelet can be used to limit the rate at which events are gathered. Setting this too low could result in relevant events not being logged, however the unlimited setting of 0 could result in a denial of service on the kubelet.

Rationale

It is important to capture all events and not restrict event creation. Events are an important source of security information and analytics that ensure that your environment is consistently monitored using the event data.

Impact

Setting this parameter to 0 could result in a denial of service condition due to excessive events being created. The cluster's event processing and storage systems should be scaled to handle expected event loads.

Audit Procedure

Audit Method 1

If using a Kubelet configuration file, check that there is an entry for --event-qps set to 0 or a value equal to or greater than 0.

First, SSH to the relevant node.

Run the following command on each node to find the appropriate Kubelet config file:

find / -name kubelet.service

The output of the above command should return the file and location /etc/systemd/system/kublet.service which is the location of the Kubelet service config file.

Open the Kubelet service config file:

sudo more etc/systemd/system/kubelet.service

Verify that the --event-qps=0.

Audit Method 2

If using the api configz endpoint consider searching for the status of "eventRecordQPS": 0 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:

kubectl proxy --port=8001 &

export HOSTNAME_PORT=localhost:8001 (example host and port number)
export NODE_NAME=10.0.10.4 (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 service config file, edit the kubelet.service file /etc/systemd/system/kubelet.service and set the below parameter:

--event-qps=0

Remediation Method 2

If using the api configz endpoint consider searching for the status of "eventRecordQPS" 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=10.0.10.4 (example node name from "kubectl get nodes")

curl -sSL "http://${HOSTNAME_PORT}/api/v1/nodes/${NODE_NAME}/proxy/configz"

For all remediations: Based on your system, restart the kubelet service and check status:

systemctl daemon-reload
systemctl restart kubelet.service
systemctl status kubelet -l

Default Value

See the OKE documentation for the default value.

References

1. https://kubernetes.io/docs/admin/kubelet/
2. https://github.com/kubernetes/kubernetes/blob/master/pkg/kubelet/apis/kubeletconfig/v1beta1/types.go
3. https://docs.cloud.oracle.com/en-us/iaas/Content/ContEng/Concepts/contengoverview.htm

CIS Controls

MITRE ATT&CK Mappings

Profile

Level 1 (Automated)