Cis Ocp V170 1.2.28

---
name: cis-ocp-v170-1.2.28
description: "Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate (Manual)"
category: cis-openshift
version: "1.7.0"
author: cyberstrike-official
tags: [cis, openshift, kubernetes, redhat, control-plane, api-server]
cis_id: "1.2.28"
cis_benchmark: "CIS Red Hat OpenShift Container Platform Benchmark v1.7.0"
tech_stack: [kubernetes, openshift, redhat]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# CIS Red Hat OpenShift Container Platform Benchmark v1.7.0 - Control 1.2.28

## Profile Applicability

- **Level:** 1

## Description

Setup TLS connection on the API server.

## Rationale

API server communication contains sensitive parameters that should remain encrypted in transit. Configure the API server to serve only HTTPS traffic.

## Impact

TLS and client certificate authentication must be configured for your Kubernetes cluster deployment. By default, OpenShift uses X.509 certificates to provide secure connections between the API server and node/kubelet. OpenShift Container Platform monitors certificates for proper validity, for the cluster certificates it issues and manages. The OpenShift Container Platform manages certificate rotation and the alerting framework has rules to help identify when a certificate issue is about to occur.

## Audit Procedure

OpenShift uses X.509 certificates to provide secure connections between API server and node/kubelet by default. OpenShift does not use values assigned to the `tls-cert-file` or `tls-private-key-file` flags. OpenShift generates the certificate files and sets the arguments appropriately.

The API server is accessible by clients external to the cluster at `api.<cluster_name>.<base_domain>`. The administrator must set a custom default certificate to be used by the API server when serving content in order to enable clients to access the API server at a different host name or without the need to distribute the cluster-managed certificate authority (CA) certificates to the clients.

Run the following command to obtain the API server TLS certificate file:

```bash
oc get configmap config -n openshift-kube-apiserver -ojson | jq -r '.data["config.yaml"]' | jq -r '.apiServerArguments."tls-cert-file"[]'
```

Verify the output is `/etc/kubernetes/static-pod-certs/secrets/service-network-serving-certkey/tls.crt`.

Run the following command to obtain the API server TLS private key file:

```bash
oc get configmap config -n openshift-kube-apiserver -ojson | jq -r '.data["config.yaml"]' | jq -r '.apiServerArguments."tls-private-key-file"[]'
```

Verify the output is `/etc/kubernetes/static-pod-certs/secrets/service-network-serving-certkey/tls.key`.

## Remediation

None.

## Default Value

By default, OpenShift uses X.509 certificates to provide secure connections between the API server and node/kubelet. OpenShift does not use values assigned to the `tls-cert-file` or `tls-private-key-file` flags.

You may optionally set a custom default certificate to be used by the API server when serving content in order to enable clients to access the API server at a different host name or without the need to distribute the cluster-managed certificate authority (CA) certificates to the clients. Follow the directions in the OpenShift documentation User-provided certificates for the API server.

## References

1. https://docs.openshift.com/container-platform/latest/security/certificates/api-server.html
2. https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/
3. https://rootsquash.com/2016/05/10/securing-the-kubernetes-api/
4. https://github.com/kelseyhightower/docker-kubernetes-tls-guide

## CIS Controls

| Controls Version | Control                                           | IG 1 | IG 2 | IG 3 |
| ---------------- | ------------------------------------------------- | ---- | ---- | ---- |
| v8               | 3.10 Encrypt Sensitive Data in Transit            |      | \*   | \*   |
| v7               | 14.4 Encrypt All Sensitive Information in Transit |      | \*   | \*   |

## MITRE ATT&CK Mappings

| Techniques / Sub-techniques | Tactics | Mitigations |
| --------------------------- | ------- | ----------- |
| T1552                       | TA0006  | M1022       |

## Profile

**Level 1** (Manual)