Cis Aks V170 3.1.2

---
name: cis-aks-v170-3.1.2
description: "Ensure that the kubelet kubeconfig file ownership is set to root:root (Automated)"
category: cis-aks
version: "1.7.0"
author: cyberstrike-official
tags: [cis, aks, kubernetes, azure, worker-node, file-ownership, kubeconfig]
cis_id: "3.1.2"
cis_benchmark: "CIS Azure Kubernetes Service (AKS) Benchmark v1.7.0"
tech_stack: [kubernetes, azure, aks]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 3.1.2 Ensure that the kubelet kubeconfig file ownership is set to root:root (Automated)

## Profile Applicability

- Level 1

## Description

If `kubelet` is running, ensure that the file ownership of its kubeconfig file is set to `root:root`.

## Rationale

The kubeconfig file for `kubelet` controls various parameters for the `kubelet` service in the worker node. You should set its file ownership to maintain the integrity of the file. The file should be owned by `root:root`.

## Impact

None

## Audit Procedure

**Method 1**

SSH to the worker nodes.

To check to see if the Kubelet Service is running:

```bash
sudo systemctl status kubelet
```

The output should return `Active: active (running) since..`.

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

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

The output of the above command should return something similar to `--kubeconfig /var/lib/kubelet/kubeconfig` which is the location of the kubeconfig file.

Run this command to obtain the kubeconfig file ownership:

```bash
stat -c %U:%G /var/lib/kubelet/kubeconfig
```

The output of the above command gives you the kubeconfig file's ownership. Verify that the ownership is set to `root:root`.

**Method 2**

Create and Run a Privileged Pod.

You will need to run a pod that is privileged enough to access the host's file system. This can be achieved by deploying a pod that uses the hostPath volume to mount the node's file system into the pod.

Here's an example of a simple pod definition that mounts the root of the host to /host within the pod:

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: file-check
spec:
  volumes:
    - name: host-root
      hostPath:
        path: /
        type: Directory
  containers:
    - name: nsenter
      image: busybox
      command: ["sleep", "3600"]
      volumeMounts:
        - name: host-root
          mountPath: /host
      securityContext:
        privileged: true
```

Save this to a file (e.g., file-check-pod.yaml) and create the pod:

```bash
kubectl apply -f file-check-pod.yaml
```

Once the pod is running, you can exec into it to check file ownership on the node:

```bash
kubectl exec -it file-check -- sh
```

Now you are in a shell inside the pod, but you can access the node's file system through the /host directory and check the ownership of the file:

```bash
ls -l /host/var/lib/kubelet/kubeconfig
```

The output of the above command gives you the kubeconfig file's ownership. Verify that the ownership is set to `root:root`.

## Remediation

Run the below command (based on the file location on your system) on each worker node. For example,

```bash
chown root:root <proxy kubeconfig file>
```

## Default Value

See the Azure AKS documentation for the default value.

## References

1. https://kubernetes.io/docs/admin/kube-proxy/
2. https://docs.microsoft.com/security/benchmark/azure/security-controls-v2-posture-vulnerability-management#pv-3-establish-secure-configurations-for-compute-resources

## CIS Controls

| Controls Version | Control                                 | IG 1 | IG 2 | IG 3 |
| ---------------- | --------------------------------------- | ---- | ---- | ---- |
| v8               | 3.3 Configure Data Access Control Lists | X    | X    | X    |
| v7               | 5.2 Maintain Secure Images              |      | X    | X    |