Cis K8s V1120 4.2.6

---
name: cis-k8s-v1120-4.2.6
description: "Ensure that the --make-iptables-util-chains argument is set to true (Automated)"
category: cis-k8s
version: "1.12.0"
author: cyberstrike-official
tags: [cis, kubernetes, worker-nodes, kubelet]
cis_id: "4.2.6"
cis_benchmark: "CIS Kubernetes Benchmark v1.12.0"
tech_stack: [kubernetes]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# CIS Kubernetes Benchmark v1.12.0 - Control 4.2.6

## Description

Allow Kubelet to manage iptables.

## Rationale

Kubelets can automatically manage the required changes to iptables based on how you choose your networking options for the pods. It is recommended to let kubelets manage the changes to iptables. This ensures that the iptables configuration remains in sync with pods networking configuration. Manually configuring iptables with dynamic pod network configuration changes might hamper the communication between pods/containers and to the outside world. You might have iptables rules too restrictive or too open.

## Impact

Kubelet would manage the iptables on the system and keep it in sync. If you are using any other iptables management solution, then there might be some conflicts.

## Audit Procedure

### Step 1: Verify via process arguments

Run the following command on each node:

```bash
ps -ef | grep kubelet
```

Verify that if the `--make-iptables-util-chains` argument exists then it is set to `true`.

If the `--make-iptables-util-chains` argument does not exist, and there is a Kubelet config file specified by `--config`, verify that the file does not set `makeIPTablesUtilChains` to `false`.

## Remediation

If using a Kubelet config file, edit the file to set `makeIPTablesUtilChains: true`.

If using command line arguments, edit the kubelet service file `/etc/kubernetes/kubelet.conf` on each worker node and remove the `--make-iptables-util-chains` argument from the `KUBELET_SYSTEM_PODS_ARGS` variable.

Based on your system, restart the `kubelet` service. For example:

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

## Default Value

By default, `--make-iptables-util-chains` argument is set to `true`.

## References

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

## CIS Controls

| Controls Version | Control                                                                                                                                                                                                      | IG 1 | IG 2 | IG 3 |
| ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---- | ---- | ---- |
| v8               | 2.5 Allowlist Authorized Software<br>Use technical controls, such as application allowlisting, to ensure that only authorized software can execute or be accessed. Reassess bi-annually, or more frequently. |      | ●    | ●    |
| v7               | 14 Controlled Access Based on the Need to Know<br>Controlled Access Based on the Need to Know                                                                                                                |      |      |      |

## Profile Applicability

- Level 1 - Worker Node

## Assessment Status

Automated