Cis Aks V170 3.2.2

---
name: cis-aks-v170-3.2.2
description: "Ensure that the --authorization-mode argument is not set to AlwaysAllow (Automated)"
category: cis-aks
version: "1.7.0"
author: cyberstrike-official
tags: [cis, aks, kubernetes, azure, kubelet, authorization, authorization-mode]
cis_id: "3.2.2"
cis_benchmark: "CIS Azure Kubernetes Service (AKS) Benchmark v1.7.0"
tech_stack: [kubernetes, azure, aks]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 3.2.2 Ensure that the --authorization-mode argument is not set to AlwaysAllow (Automated)

## Profile Applicability

- Level 1

## Description

Do not allow all requests. Enable explicit authorization.

## Rationale

Kubelets, by default, allow all authenticated requests (even anonymous ones) without needing explicit authorization checks from the apiserver. You should restrict this behavior and only allow explicitly authorized requests.

## Impact

Unauthorized requests will be denied.

## Audit Procedure

**Audit Method 1:**

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

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
sudo more /etc/kubernetes/kubelet/kubelet-config.json
```

Verify that the `"authentication": {"webhook": { "enabled":` is set to `true`.

If the `"authentication": {"mode": {` argument is present check that it is not set to `AlwaysAllow`. If it is not present check that there is a Kubelet config file specified by `--config`, and that file sets `"authentication": {"mode": {` to something other than `AlwaysAllow`.

**Audit Method 2:**

If using the api configz endpoint consider searching for the status of `authentication... "webhook":{"enabled":true}` 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`

```bash
kubectl proxy --port=8001 &

export HOSTNAME_PORT=localhost:8001 (example host and port number)
export NODE_NAME=ip-192.168.31.226.aks.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 below parameter to false:

```json
"authentication"... "webhook":{"enabled":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.

```
--authorization-mode=Webhook
```

**Remediation Method 3:**

If using the api configz endpoint consider searching for the status of `"authentication.*webhook":{"enabled":"true"` 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](https://kubernetes.io/docs/tasks/administer-cluster/reconfigure-kubelet/), and then rerun the curl statement from audit process to check for kubelet configuration changes.

**For all three remediations:** 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 Azure AKS documentation for the default value.

## References

1. https://kubernetes.io/docs/admin/kubelet/
2. https://kubernetes.io/docs/admin/kubelet-authentication-authorization/#kubelet-authentication
3. https://kubernetes.io/docs/tasks/administer-cluster/reconfigure-kubelet/
4. https://docs.microsoft.com/security/benchmark/azure/security-controls-v2-governance-strategy#gs-6-define-identity-and-privileged-access-strategy

## CIS Controls

| Controls Version | Control                                        | IG 1 | IG 2 | IG 3 |
| ---------------- | ---------------------------------------------- | ---- | ---- | ---- |
| v8               | 6 Access Control Management                    |      |      |      |
| v7               | 14 Controlled Access Based on the Need to Know |      |      |      |