Cis Gke V170 3.2.4

---
name: cis-gke-v170-3.2.4
description: "Ensure that the --read-only-port is disabled (Automated)"
category: cis-gke
version: "1.7.0"
author: cyberstrike-official
tags: [cis, gke, kubernetes, gcp, kubelet, authentication, authorization, tls, event-capture, certificate-rotation]
cis_id: "3.2.4"
cis_benchmark: "CIS Google Kubernetes Engine (GKE) Benchmark v1.7.0"
tech_stack: [kubernetes, gcp, gke]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 3.2.4 Ensure that the --read-only-port is disabled (Automated)

## Profile Applicability

- Level 1

## Description

Disable the read-only port.

## Rationale

The Kubelet process provides a read-only API in addition to the main Kubelet API. Unauthenticated access is provided to this read-only API which could possibly retrieve potentially sensitive information about the cluster.

## Impact

Removal of the read-only port will require that any service which made use of it will need to be re-configured to use the main Kubelet API.

## Audit

If using a Kubelet configuration file, check that there is an entry for `authentication: anonymous: enabled` set to `0`.

First, SSH to the relevant node.

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

```bash
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:

```bash
cat /etc/kubernetes/kubelet/kubelet-config.json
```

Verify that the `--read-only-port` argument exists and is set to `0`.

If the `--read-only-port` argument is not present, check that there is a Kubelet config file specified by `--config`. Check that if there is a `readOnlyPort` entry in the file, it is set to `0`.

## Remediation

If modifying the Kubelet config file, edit the kubelet-config.json file `/etc/kubernetes/kubelet/kubelet-config.json` and set the below parameter to 0

```json
"readOnlyPort": 0
```

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.

```
--read-only-port=0
```

For each remediation:

Based on your system, restart the `kubelet` service and check status

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

## Default Value

See the GKE documentation for the default value.

## References

1. https://kubernetes.io/docs/admin/kubelet/

## CIS Controls

| Controls Version | Control                                                                                                                                                                                                           | IG 1 | IG 2 | IG 3 |
| ---------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---- | ---- | ---- |
| v8               | **12.6 Use of Secure Network Management and Communication Protocols** - Use secure network management and communication protocols (e.g., 802.1X, Wi-Fi Protected Access 2 (WPA2) Enterprise or greater).          |      |      |      |
| v7               | **9.2 Ensure Only Approved Ports, Protocols and Services Are Running** - Ensure that only network ports, protocols, and services listening on a system with validated business needs, are running on each system. |      |      |      |