CIS Kubernetes Benchmark v1.5 - Rancher v2.3.5 with Kubernetes v1.15

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Overview

This document is a companion to the Rancher v2.3.5 security hardening guide. The hardening guide provides prescriptive guidance for hardening a production installation of Rancher, and this benchmark guide is meant to help you evaluate the level of security of the hardened cluster against each control in the benchmark.

This guide corresponds to specific versions of the hardening guide, Rancher, Kubernetes, and the CIS Benchmark:

Self Assessment Guide Version Rancher Version Hardening Guide Version Kubernetes Version CIS Benchmark Version
Self Assessment Guide v2.3.5 Rancher v2.3.5 Hardening Guide v2.3.5 Kubernetes v1.15 Benchmark v1.5

Because Rancher and RKE install Kubernetes services as Docker containers, many of the control verification checks in the CIS Kubernetes Benchmark don’t apply and will have a result of Not Applicable. This guide will walk through the various controls and provide updated example commands to audit compliance in Rancher-created clusters.

This document is to be used by Rancher operators, security teams, auditors and decision makers.

For more detail about each audit, including rationales and remediations for failing tests, you can refer to the corresponding section of the CIS Kubernetes Benchmark v1.5. You can download the benchmark after logging in to CISecurity.org.

Testing controls methodology

Rancher and RKE install Kubernetes services via Docker containers. Configuration is defined by arguments passed to the container at the time of initialization, not via configuration files.

Where control audits differ from the original CIS benchmark, the audit commands specific to Rancher Labs are provided for testing. When performing the tests, you will need access to the Docker command line on the hosts of all three RKE roles. The commands also make use of the the jq and kubectl (with valid config) tools to and are required in the testing and evaluation of test results.

NOTE: only scored tests are covered in this guide.

Controls


1 Master Node Security Configuration

1.1 Master Node Configuration Files

1.1.1 Ensure that the API server pod specification file permissions are set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the API server. All configuration is passed in as arguments at container run time.

1.1.2 Ensure that the API server pod specification file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the API server. All configuration is passed in as arguments at container run time.

1.1.3 Ensure that the controller manager pod specification file permissions are set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the controller manager. All configuration is passed in as arguments at container run time.

1.1.4 Ensure that the controller manager pod specification file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the controller manager. All configuration is passed in as arguments at container run time.

1.1.5 Ensure that the scheduler pod specification file permissions are set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the scheduler. All configuration is passed in as arguments at container run time.

1.1.6 Ensure that the scheduler pod specification file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the scheduler. All configuration is passed in as arguments at container run time.

1.1.7 Ensure that the etcd pod specification file permissions are set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for etcd. All configuration is passed in as arguments at container run time.

1.1.8 Ensure that the etcd pod specification file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for etcd. All configuration is passed in as arguments at container run time.

1.1.11 Ensure that the etcd data directory permissions are set to 700 or more restrictive (Scored)

Result: PASS

Remediation: On the etcd server node, get the etcd data directory, passed as an argument --data-dir, from the below command:

ps -ef | grep etcd

Run the below command (based on the etcd data directory found above). For example,

chmod 700 /var/lib/etcd

Audit Script: 1.1.11.sh

#!/bin/bash -e

etcd_bin=${1}

test_dir=$(ps -ef | grep ${etcd_bin} | grep -- --data-dir | sed 's%.*data-dir[= ]\([^ ]*\).*%\1%')

docker inspect etcd | jq -r '.[].HostConfig.Binds[]' | grep "${test_dir}" | cut -d ":" -f 1 | xargs stat -c %a

Audit Execution:

./1.1.11.sh etcd

Expected result:

'700' is equal to '700'

1.1.12 Ensure that the etcd data directory ownership is set to etcd:etcd (Scored)

Result: PASS

Remediation: On the etcd server node, get the etcd data directory, passed as an argument --data-dir, from the below command:

ps -ef | grep etcd

Run the below command (based on the etcd data directory found above). For example,

chown etcd:etcd /var/lib/etcd

Audit Script: 1.1.12.sh

#!/bin/bash -e

etcd_bin=${1}

test_dir=$(ps -ef | grep ${etcd_bin} | grep -- --data-dir | sed 's%.*data-dir[= ]\([^ ]*\).*%\1%')

docker inspect etcd | jq -r '.[].HostConfig.Binds[]' | grep "${test_dir}" | cut -d ":" -f 1 | xargs stat -c %U:%G

Audit Execution:

./1.1.12.sh etcd

Expected result:

'etcd:etcd' is present

1.1.13 Ensure that the admin.conf file permissions are set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE does not store the kubernetes default kubeconfig credentials file on the nodes. It’s presented to user where RKE is run. We recommend that this kube_config_cluster.yml file be kept in secure store.

1.1.14 Ensure that the admin.conf file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE does not store the kubernetes default kubeconfig credentials file on the nodes. It’s presented to user where RKE is run. We recommend that this kube_config_cluster.yml file be kept in secure store.

1.1.15 Ensure that the scheduler.conf file permissions are set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the scheduler. All configuration is passed in as arguments at container run time.

1.1.16 Ensure that the scheduler.conf file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the scheduler. All configuration is passed in as arguments at container run time.

1.1.17 Ensure that the controller-manager.conf file permissions are set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the controller manager. All configuration is passed in as arguments at container run time.

1.1.18 Ensure that the controller-manager.conf file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the controller manager. All configuration is passed in as arguments at container run time.

1.1.19 Ensure that the Kubernetes PKI directory and file ownership is set to root:root (Scored)

Result: PASS

Remediation: Run the below command (based on the file location on your system) on the master node. For example,

chown -R root:root /etc/kubernetes/ssl

Audit:

stat -c %U:%G /etc/kubernetes/ssl

Expected result:

'root:root' is present

1.1.20 Ensure that the Kubernetes PKI certificate file permissions are set to 644 or more restrictive (Scored)

Result: PASS

Remediation: Run the below command (based on the file location on your system) on the master node. For example,

chmod -R 644 /etc/kubernetes/ssl

Audit Script: check_files_permissions.sh

#!/usr/bin/env bash

# This script is used to ensure the file permissions are set to 644 or
# more restrictive for all files in a given directory or a wildcard
# selection of files
#
# inputs:
#   $1 = /full/path/to/directory or /path/to/fileswithpattern
#                                   ex: !(*key).pem
#
#   $2 (optional) = permission (ex: 600)
#
# outputs:
#   true/false

# Turn on "extended glob" for use of '!' in wildcard
shopt -s extglob

# Turn off history to avoid surprises when using '!'
set -H

USER_INPUT=$1

if [[ "${USER_INPUT}" == "" ]]; then
  echo "false"
  exit
fi


if [[ -d ${USER_INPUT} ]]; then
  PATTERN="${USER_INPUT}/*"
else
  PATTERN="${USER_INPUT}"
fi

PERMISSION=""
if [[ "$2" != "" ]]; then
  PERMISSION=$2
fi

FILES_PERMISSIONS=$(stat -c %n\ %a ${PATTERN})

while read -r fileInfo; do
  p=$(echo ${fileInfo} | cut -d' ' -f2)

  if [[ "${PERMISSION}" != "" ]]; then
    if [[ "$p" != "${PERMISSION}" ]]; then
      echo "false"
      exit
    fi
  else
    if [[ "$p" != "644" && "$p" != "640" && "$p" != "600" ]]; then
      echo "false"
      exit
    fi
  fi
done <<< "${FILES_PERMISSIONS}"


echo "true"
exit

Audit Execution:

./check_files_permissions.sh '/etc/kubernetes/ssl/*.pem'

Expected result:

'true' is present

1.1.21 Ensure that the Kubernetes PKI key file permissions are set to 600 (Scored)

Result: PASS

Remediation: Run the below command (based on the file location on your system) on the master node. For example,

chmod -R 600 /etc/kubernetes/ssl/certs/serverca

Audit Script: 1.1.21.sh

#!/bin/bash -e
check_dir=${1:-/etc/kubernetes/ssl}

for file in $(find ${check_dir} -name "*key.pem"); do
	file_permission=$(stat -c %a ${file})
  if [[ "${file_permission}" == "600" ]]; then
    continue
  else
    echo "FAIL: ${file} ${file_permission}"
    exit 1
  fi
done

echo "pass"

Audit Execution:

./1.1.21.sh /etc/kubernetes/ssl

Expected result:

'pass' is present

1.2 API Server

1.2.2 Ensure that the --basic-auth-file argument is not set (Scored)

Result: PASS

Remediation: Follow the documentation and configure alternate mechanisms for authentication. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and remove the --basic-auth-file=<filename> parameter.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--basic-auth-file' is not present

1.2.3 Ensure that the --token-auth-file parameter is not set (Scored)

Result: PASS

Remediation: Follow the documentation and configure alternate mechanisms for authentication. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and remove the --token-auth-file=<filename> parameter.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--token-auth-file' is not present

1.2.4 Ensure that the --kubelet-https argument is set to true (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and remove the --kubelet-https parameter.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--kubelet-https' is present OR '--kubelet-https' is not present

1.2.5 Ensure that the --kubelet-client-certificate and --kubelet-client-key arguments are set as appropriate (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and set up the TLS connection between the apiserver and kubelets. Then, edit API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the kubelet client certificate and key parameters as below.

--kubelet-client-certificate=<path/to/client-certificate-file>
--kubelet-client-key=<path/to/client-key-file>

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--kubelet-client-certificate' is present AND '--kubelet-client-key' is present

1.2.6 Ensure that the --kubelet-certificate-authority argument is set as appropriate (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and setup the TLS connection between the apiserver and kubelets. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --kubelet-certificate-authority parameter to the path to the cert file for the certificate authority. --kubelet-certificate-authority=<ca-string>

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--kubelet-certificate-authority' is present

1.2.7 Ensure that the --authorization-mode argument is not set to AlwaysAllow (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --authorization-mode parameter to values other than AlwaysAllow. One such example could be as below.

--authorization-mode=RBAC

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'Node,RBAC' not have 'AlwaysAllow'

1.2.8 Ensure that the --authorization-mode argument includes Node (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --authorization-mode parameter to a value that includes Node.

--authorization-mode=Node,RBAC

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'Node,RBAC' has 'Node'

1.2.9 Ensure that the --authorization-mode argument includes RBAC (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --authorization-mode parameter to a value that includes RBAC, for example:

--authorization-mode=Node,RBAC

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'Node,RBAC' has 'RBAC'

1.2.11 Ensure that the admission control plugin AlwaysAdmit is not set (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and either remove the --enable-admission-plugins parameter, or set it to a value that does not include AlwaysAdmit.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,DefaultTolerationSeconds,MutatingAdmissionWebhook,ValidatingAdmissionWebhook,ResourceQuota,NodeRestriction,Priority,TaintNodesByCondition,PersistentVolumeClaimResize,PodSecurityPolicy,EventRateLimit' not have 'AlwaysAdmit' OR '--enable-admission-plugins' is not present

1.2.14 Ensure that the admission control plugin ServiceAccount is set (Scored)

Result: PASS

Remediation: Follow the documentation and create ServiceAccount objects as per your environment. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and ensure that the --disable-admission-plugins parameter is set to a value that does not include ServiceAccount.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,DefaultTolerationSeconds,MutatingAdmissionWebhook,ValidatingAdmissionWebhook,ResourceQuota,NodeRestriction,Priority,TaintNodesByCondition,PersistentVolumeClaimResize,PodSecurityPolicy,EventRateLimit' has 'ServiceAccount' OR '--enable-admission-plugins' is not present

1.2.15 Ensure that the admission control plugin NamespaceLifecycle is set (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --disable-admission-plugins parameter to ensure it does not include NamespaceLifecycle.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--disable-admission-plugins' is present OR '--disable-admission-plugins' is not present

1.2.16 Ensure that the admission control plugin PodSecurityPolicy is set (Scored)

Result: PASS

Remediation: Follow the documentation and create Pod Security Policy objects as per your environment. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --enable-admission-plugins parameter to a value that includes PodSecurityPolicy:

--enable-admission-plugins=...,PodSecurityPolicy,...

Then restart the API Server.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,DefaultTolerationSeconds,MutatingAdmissionWebhook,ValidatingAdmissionWebhook,ResourceQuota,NodeRestriction,Priority,TaintNodesByCondition,PersistentVolumeClaimResize,PodSecurityPolicy,EventRateLimit' has 'PodSecurityPolicy'

1.2.17 Ensure that the admission control plugin NodeRestriction is set (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and configure NodeRestriction plug-in on kubelets. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --enable-admission-plugins parameter to a value that includes NodeRestriction.

--enable-admission-plugins=...,NodeRestriction,...

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,DefaultTolerationSeconds,MutatingAdmissionWebhook,ValidatingAdmissionWebhook,ResourceQuota,NodeRestriction,Priority,TaintNodesByCondition,PersistentVolumeClaimResize,PodSecurityPolicy,EventRateLimit' has 'NodeRestriction'

1.2.18 Ensure that the --insecure-bind-address argument is not set (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and remove the --insecure-bind-address parameter.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--insecure-bind-address' is not present

1.2.19 Ensure that the --insecure-port argument is set to 0 (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the below parameter.

--insecure-port=0

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'0' is equal to '0'

1.2.20 Ensure that the --secure-port argument is not set to 0 (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and either remove the --secure-port parameter or set it to a different (non-zero) desired port.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

6443 is greater than 0 OR '--secure-port' is not present

1.2.21 Ensure that the --profiling argument is set to false (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the below parameter.

--profiling=false

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'false' is equal to 'false'

1.2.22 Ensure that the --audit-log-path argument is set (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --audit-log-path parameter to a suitable path and file where you would like audit logs to be written, for example:

--audit-log-path=/var/log/apiserver/audit.log

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--audit-log-path' is present

1.2.23 Ensure that the --audit-log-maxage argument is set to 30 or as appropriate (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --audit-log-maxage parameter to 30 or as an appropriate number of days:

--audit-log-maxage=30

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

30 is greater or equal to 30

1.2.24 Ensure that the --audit-log-maxbackup argument is set to 10 or as appropriate (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --audit-log-maxbackup parameter to 10 or to an appropriate value.

--audit-log-maxbackup=10

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

10 is greater or equal to 10

1.2.25 Ensure that the --audit-log-maxsize argument is set to 100 or as appropriate (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --audit-log-maxsize parameter to an appropriate size in MB. For example, to set it as 100 MB:

--audit-log-maxsize=100

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

100 is greater or equal to 100

1.2.26 Ensure that the --request-timeout argument is set as appropriate (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml and set the below parameter as appropriate and if needed. For example,

--request-timeout=300s

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--request-timeout' is not present OR '--request-timeout' is present

1.2.27 Ensure that the --service-account-lookup argument is set to true (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the below parameter.

--service-account-lookup=true

Alternatively, you can delete the --service-account-lookup parameter from this file so that the default takes effect.

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--service-account-lookup' is not present OR 'true' is equal to 'true'

1.2.28 Ensure that the --service-account-key-file argument is set as appropriate (Scored)

Result: PASS

Remediation: Edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --service-account-key-file parameter to the public key file for service accounts:

--service-account-key-file=<filename>

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--service-account-key-file' is present

1.2.29 Ensure that the --etcd-certfile and --etcd-keyfile arguments are set as appropriate (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and set up the TLS connection between the apiserver and etcd. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the etcd certificate and key file parameters.

--etcd-certfile=<path/to/client-certificate-file>
--etcd-keyfile=<path/to/client-key-file>

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--etcd-certfile' is present AND '--etcd-keyfile' is present

1.2.30 Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and set up the TLS connection on the apiserver. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the TLS certificate and private key file parameters.

--tls-cert-file=<path/to/tls-certificate-file>
--tls-private-key-file=<path/to/tls-key-file>

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--tls-cert-file' is present AND '--tls-private-key-file' is present

1.2.31 Ensure that the --client-ca-file argument is set as appropriate (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and set up the TLS connection on the apiserver. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the client certificate authority file.

--client-ca-file=<path/to/client-ca-file>

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--client-ca-file' is present

1.2.32 Ensure that the --etcd-cafile argument is set as appropriate (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and set up the TLS connection between the apiserver and etcd. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the etcd certificate authority file parameter.

--etcd-cafile=<path/to/ca-file>

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--etcd-cafile' is present

1.2.33 Ensure that the --encryption-provider-config argument is set as appropriate (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and configure a EncryptionConfig file. Then, edit the API server pod specification file /etc/kubernetes/manifests/kube-apiserver.yaml on the master node and set the --encryption-provider-config parameter to the path of that file:

--encryption-provider-config=</path/to/EncryptionConfig/File>

Audit:

/bin/ps -ef | grep kube-apiserver | grep -v grep

Expected result:

'--encryption-provider-config' is present

1.2.34 Ensure that encryption providers are appropriately configured (Scored)

Result: PASS

Remediation: Follow the Kubernetes documentation and configure a EncryptionConfig file. In this file, choose aescbc, kms or secretbox as the encryption provider.

Audit Script: 1.2.34.sh

#!/bin/bash -e

check_file=${1}

grep -q -E 'aescbc|kms|secretbox' ${check_file}
if [ $? -eq 0 ]; then
  echo "--pass"
  exit 0
else
  echo "fail: encryption provider found in ${check_file}"
  exit 1
fi

Audit Execution:

./1.2.34.sh /etc/kubernetes/ssl/encryption.yaml

Expected result:

'--pass' is present

1.3 Controller Manager

1.3.1 Ensure that the --terminated-pod-gc-threshold argument is set as appropriate (Scored)

Result: PASS

Remediation: Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the master node and set the --terminated-pod-gc-threshold to an appropriate threshold, for example:

--terminated-pod-gc-threshold=10

Audit:

/bin/ps -ef | grep kube-controller-manager | grep -v grep

Expected result:

'--terminated-pod-gc-threshold' is present

1.3.2 Ensure that the --profiling argument is set to false (Scored)

Result: PASS

Remediation: Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the master node and set the below parameter.

--profiling=false

Audit:

/bin/ps -ef | grep kube-controller-manager | grep -v grep

Expected result:

'false' is equal to 'false'

1.3.3 Ensure that the --use-service-account-credentials argument is set to true (Scored)

Result: PASS

Remediation: Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the master node to set the below parameter.

--use-service-account-credentials=true

Audit:

/bin/ps -ef | grep kube-controller-manager | grep -v grep

Expected result:

'true' is not equal to 'false'

1.3.4 Ensure that the --service-account-private-key-file argument is set as appropriate (Scored)

Result: PASS

Remediation: Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the master node and set the --service-account-private-key-file parameter to the private key file for service accounts.

--service-account-private-key-file=<filename>

Audit:

/bin/ps -ef | grep kube-controller-manager | grep -v grep

Expected result:

'--service-account-private-key-file' is present

1.3.5 Ensure that the --root-ca-file argument is set as appropriate (Scored)

Result: PASS

Remediation: Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the master node and set the --root-ca-file parameter to the certificate bundle file`.

--root-ca-file=<path/to/file>

Audit:

/bin/ps -ef | grep kube-controller-manager | grep -v grep

Expected result:

'--root-ca-file' is present

1.3.6 Ensure that the RotateKubeletServerCertificate argument is set to true (Scored)

Result: PASS

Remediation: Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the master node and set the --feature-gates parameter to include RotateKubeletServerCertificate=true.

--feature-gates=RotateKubeletServerCertificate=true

Audit:

/bin/ps -ef | grep kube-controller-manager | grep -v grep

Expected result:

'RotateKubeletServerCertificate=true' is equal to 'RotateKubeletServerCertificate=true'

1.3.7 Ensure that the --bind-address argument is set to 127.0.0.1 (Scored)

Result: PASS

Remediation: Edit the Controller Manager pod specification file /etc/kubernetes/manifests/kube-controller-manager.yaml on the master node and ensure the correct value for the --bind-address parameter.

Audit:

/bin/ps -ef | grep kube-controller-manager | grep -v grep

Expected result:

'--bind-address' is present OR '--bind-address' is not present

1.4 Scheduler

1.4.1 Ensure that the --profiling argument is set to false (Scored)

Result: PASS

Remediation: Edit the Scheduler pod specification file /etc/kubernetes/manifests/kube-scheduler.yaml file on the master node and set the below parameter.

--profiling=false

Audit:

/bin/ps -ef | grep kube-scheduler | grep -v grep

Expected result:

'false' is equal to 'false'

1.4.2 Ensure that the --bind-address argument is set to 127.0.0.1 (Scored)

Result: PASS

Remediation: Edit the Scheduler pod specification file /etc/kubernetes/manifests/kube-scheduler.yaml on the master node and ensure the correct value for the --bind-address parameter.

Audit:

/bin/ps -ef | grep kube-scheduler | grep -v grep

Expected result:

'--bind-address' is present OR '--bind-address' is not present

2 Etcd Node Configuration

2 Etcd Node Configuration Files

2.1 Ensure that the --cert-file and --key-file arguments are set as appropriate (Scored)

Result: PASS

Remediation: Follow the etcd service documentation and configure TLS encryption. Then, edit the etcd pod specification file /etc/kubernetes/manifests/etcd.yaml on the master node and set the below parameters.

--cert-file=</path/to/ca-file>
--key-file=</path/to/key-file>

Audit:

/bin/ps -ef | /bin/grep etcd | /bin/grep -v grep

Expected result:

'--cert-file' is present AND '--key-file' is present

2.2 Ensure that the --client-cert-auth argument is set to true (Scored)

Result: PASS

Remediation: Edit the etcd pod specification file /etc/kubernetes/manifests/etcd.yaml on the master node and set the below parameter.

--client-cert-auth="true"

Audit:

/bin/ps -ef | /bin/grep etcd | /bin/grep -v grep

Expected result:

'true' is equal to 'true'

2.3 Ensure that the --auto-tls argument is not set to true (Scored)

Result: PASS

Remediation: Edit the etcd pod specification file /etc/kubernetes/manifests/etcd.yaml on the master node and either remove the --auto-tls parameter or set it to false.

 --auto-tls=false

Audit:

/bin/ps -ef | /bin/grep etcd | /bin/grep -v grep

Expected result:

'--auto-tls' is not present OR '--auto-tls' is not present

2.4 Ensure that the --peer-cert-file and --peer-key-file arguments are set as appropriate (Scored)

Result: PASS

Remediation: Follow the etcd service documentation and configure peer TLS encryption as appropriate for your etcd cluster. Then, edit the etcd pod specification file /etc/kubernetes/manifests/etcd.yaml on the master node and set the below parameters.

--peer-client-file=</path/to/peer-cert-file>
--peer-key-file=</path/to/peer-key-file>

Audit:

/bin/ps -ef | /bin/grep etcd | /bin/grep -v grep

Expected result:

'--peer-cert-file' is present AND '--peer-key-file' is present

2.5 Ensure that the --peer-client-cert-auth argument is set to true (Scored)

Result: PASS

Remediation: Edit the etcd pod specification file /etc/kubernetes/manifests/etcd.yaml on the master node and set the below parameter.

--peer-client-cert-auth=true

Audit:

/bin/ps -ef | /bin/grep etcd | /bin/grep -v grep

Expected result:

'true' is equal to 'true'

2.6 Ensure that the --peer-auto-tls argument is not set to true (Scored)

Result: PASS

Remediation: Edit the etcd pod specification file /etc/kubernetes/manifests/etcd.yaml on the master node and either remove the --peer-auto-tls parameter or set it to false.

--peer-auto-tls=false

Audit:

/bin/ps -ef | /bin/grep etcd | /bin/grep -v grep

Expected result:

'--peer-auto-tls' is not present OR '--peer-auto-tls' is present

3 Control Plane Configuration

3.2 Logging

3.2.1 Ensure that a minimal audit policy is created (Scored)

Result: PASS

Remediation: Create an audit policy file for your cluster.

Audit Script: 3.2.1.sh

#!/bin/bash -e

api_server_bin=${1}

/bin/ps -ef | /bin/grep ${api_server_bin} | /bin/grep -v ${0} | /bin/grep -v grep

Audit Execution:

./3.2.1.sh kube-apiserver

Expected result:

'--audit-policy-file' is present

4 Worker Node Security Configuration

4.1 Worker Node Configuration Files

4.1.1 Ensure that the kubelet service file permissions are set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the kubelet service. All configuration is passed in as arguments at container run time.

4.1.2 Ensure that the kubelet service file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the kubelet service. All configuration is passed in as arguments at container run time.

4.1.3 Ensure that the proxy kubeconfig file permissions are set to 644 or more restrictive (Scored)

Result: PASS

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

chmod 644 /etc/kubernetes/ssl/kubecfg-kube-proxy.yaml

Audit:

/bin/sh -c 'if test -e /etc/kubernetes/ssl/kubecfg-kube-proxy.yaml; then stat -c %a /etc/kubernetes/ssl/kubecfg-kube-proxy.yaml; fi' 

Expected result:

'644' is present OR '640' is present OR '600' is equal to '600' OR '444' is present OR '440' is present OR '400' is present OR '000' is present

4.1.4 Ensure that the proxy kubeconfig file ownership is set to root:root (Scored)

Result: PASS

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

chown root:root /etc/kubernetes/ssl/kubecfg-kube-proxy.yaml

Audit:

/bin/sh -c 'if test -e /etc/kubernetes/ssl/kubecfg-kube-proxy.yaml; then stat -c %U:%G /etc/kubernetes/ssl/kubecfg-kube-proxy.yaml; fi' 

Expected result:

'root:root' is present

4.1.5 Ensure that the kubelet.conf file permissions are set to 644 or more restrictive (Scored)

Result: PASS

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

chmod 644 /etc/kubernetes/ssl/kubecfg-kube-node.yaml

Audit:

/bin/sh -c 'if test -e /etc/kubernetes/ssl/kubecfg-kube-node.yaml; then stat -c %a /etc/kubernetes/ssl/kubecfg-kube-node.yaml; fi' 

Expected result:

'644' is present OR '640' is present OR '600' is equal to '600' OR '444' is present OR '440' is present OR '400' is present OR '000' is present

4.1.6 Ensure that the kubelet.conf file ownership is set to root:root (Scored)

Result: PASS

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

chown root:root /etc/kubernetes/ssl/kubecfg-kube-node.yaml

Audit:

/bin/sh -c 'if test -e /etc/kubernetes/ssl/kubecfg-kube-node.yaml; then stat -c %U:%G /etc/kubernetes/ssl/kubecfg-kube-node.yaml; fi' 

Expected result:

'root:root' is equal to 'root:root'

4.1.7 Ensure that the certificate authorities file permissions are set to 644 or more restrictive (Scored)

Result: PASS

Remediation: Run the following command to modify the file permissions of the

--client-ca-file chmod 644 <filename>

Audit:

stat -c %a /etc/kubernetes/ssl/kube-ca.pem

Expected result:

'644' is equal to '644' OR '640' is present OR '600' is present

4.1.8 Ensure that the client certificate authorities file ownership is set to root:root (Scored)

Result: PASS

Remediation: Run the following command to modify the ownership of the --client-ca-file.

chown root:root <filename>

Audit:

/bin/sh -c 'if test -e /etc/kubernetes/ssl/kube-ca.pem; then stat -c %U:%G /etc/kubernetes/ssl/kube-ca.pem; fi' 

Expected result:

'root:root' is equal to 'root:root'

4.1.9 Ensure that the kubelet configuration file has permissions set to 644 or more restrictive (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the kubelet service. All configuration is passed in as arguments at container run time.

4.1.10 Ensure that the kubelet configuration file ownership is set to root:root (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the kubelet service. All configuration is passed in as arguments at container run time.

4.2 Kubelet

4.2.1 Ensure that the --anonymous-auth argument is set to false (Scored)

Result: PASS

Remediation: If using a Kubelet config file, edit the file to set authentication: anonymous: enabled to false. If using executable arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and set the below parameter in KUBELET_SYSTEM_PODS_ARGS variable.

--anonymous-auth=false

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

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'false' is equal to 'false'

4.2.2 Ensure that the --authorization-mode argument is not set to AlwaysAllow (Scored)

Result: PASS

Remediation: If using a Kubelet config file, edit the file to set authorization: mode to Webhook. If using executable arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and set the below parameter in KUBELET_AUTHZ_ARGS variable.

--authorization-mode=Webhook

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

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'Webhook' not have 'AlwaysAllow'

4.2.3 Ensure that the --client-ca-file argument is set as appropriate (Scored)

Result: PASS

Remediation: If using a Kubelet config file, edit the file to set authentication: x509: clientCAFile to the location of the client CA file. If using command line arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and set the below parameter in KUBELET_AUTHZ_ARGS variable.

--client-ca-file=<path/to/client-ca-file>

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

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'--client-ca-file' is present

4.2.4 Ensure that the --read-only-port argument is set to 0 (Scored)

Result: PASS

Remediation: If using a Kubelet config file, edit the file to set readOnlyPort to 0. If using command line arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and set the below parameter in KUBELET_SYSTEM_PODS_ARGS variable.

--read-only-port=0

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

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'0' is equal to '0'

4.2.5 Ensure that the --streaming-connection-idle-timeout argument is not set to 0 (Scored)

Result: PASS

Remediation: If using a Kubelet config file, edit the file to set streamingConnectionIdleTimeout to a value other than 0. If using command line arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and set the below parameter in KUBELET_SYSTEM_PODS_ARGS variable.

--streaming-connection-idle-timeout=5m

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

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'30m' is not equal to '0' OR '--streaming-connection-idle-timeout' is not present

4.2.6 Ensure that the --protect-kernel-defaults argument is set to true (Scored)

Result: PASS

Remediation: If using a Kubelet config file, edit the file to set protectKernelDefaults: true. If using command line arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and set the below parameter in KUBELET_SYSTEM_PODS_ARGS variable.

--protect-kernel-defaults=true

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

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'true' is equal to 'true'

4.2.7 Ensure that the --make-iptables-util-chains argument is set to true (Scored)

Result: PASS

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/systemd/system/kubelet.service.d/10-kubeadm.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:

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'true' is equal to 'true' OR '--make-iptables-util-chains' is not present

4.2.10 Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate (Scored)

Result: Not Applicable

Remediation: RKE doesn’t require or maintain a configuration file for the kubelet service. All configuration is passed in as arguments at container run time.

4.2.11 Ensure that the --rotate-certificates argument is not set to false (Scored)

Result: PASS

Remediation: If using a Kubelet config file, edit the file to add the line rotateCertificates: true or remove it altogether to use the default value. If using command line arguments, edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and remove --rotate-certificates=false argument from the KUBELET_CERTIFICATE_ARGS variable. Based on your system, restart the kubelet service. For example:

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'--rotate-certificates' is present OR '--rotate-certificates' is not present

4.2.12 Ensure that the RotateKubeletServerCertificate argument is set to true (Scored)

Result: PASS

Remediation: Edit the kubelet service file /etc/systemd/system/kubelet.service.d/10-kubeadm.conf on each worker node and set the below parameter in KUBELET_CERTIFICATE_ARGS variable.

--feature-gates=RotateKubeletServerCertificate=true

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

systemctl daemon-reload
systemctl restart kubelet.service

Audit:

/bin/ps -fC kubelet

Audit Config:

/bin/cat /var/lib/kubelet/config.yaml

Expected result:

'true' is equal to 'true'

5 Kubernetes Policies

5.1 RBAC and Service Accounts

5.1.5 Ensure that default service accounts are not actively used. (Scored)

Result: PASS

Remediation: Create explicit service accounts wherever a Kubernetes workload requires specific access to the Kubernetes API server. Modify the configuration of each default service account to include this value

automountServiceAccountToken: false

Audit Script: 5.1.5.sh

#!/bin/bash

export KUBECONFIG=${KUBECONFIG:-/root/.kube/config}

kubectl version > /dev/null
if [ $? -ne 0 ]; then
  echo "fail: kubectl failed"
  exit 1
fi

accounts="$(kubectl --kubeconfig=${KUBECONFIG} get serviceaccounts -A -o json | jq -r '.items[] | select(.metadata.name=="default") | select((.automountServiceAccountToken == null) or (.automountServiceAccountToken == true)) | "fail \(.metadata.name) \(.metadata.namespace)"')"

if [[ "${accounts}" != "" ]]; then
  echo "fail: automountServiceAccountToken not false for accounts: ${accounts}"
  exit 1
fi

default_binding="$(kubectl get rolebindings,clusterrolebindings -A -o json | jq -r '.items[] | select(.subjects[].kind=="ServiceAccount" and .subjects[].name=="default" and .metadata.name=="default").metadata.uid' | wc -l)"

if [[ "${default_binding}" -gt 0 ]]; then
	echo "fail: default service accounts have non default bindings"
	exit 1
fi

echo "--pass"
exit 0

Audit Execution:

./5.1.5.sh 

Expected result:

'--pass' is present

5.2 Pod Security Policies

5.2.2 Minimize the admission of containers wishing to share the host process ID namespace (Scored)

Result: PASS

Remediation: Create a PSP as described in the Kubernetes documentation, ensuring that the .spec.hostPID field is omitted or set to false.

Audit:

kubectl --kubeconfig=/root/.kube/config get psp -o json | jq .items[] | jq -r 'select((.spec.hostPID == null) or (.spec.hostPID == false))' | jq .metadata.name | wc -l | xargs -I {} echo '--count={}'

Expected result:

1 is greater than 0

5.2.3 Minimize the admission of containers wishing to share the host IPC namespace (Scored)

Result: PASS

Remediation: Create a PSP as described in the Kubernetes documentation, ensuring that the .spec.hostIPC field is omitted or set to false.

Audit:

kubectl --kubeconfig=/root/.kube/config get psp -o json | jq .items[] | jq -r 'select((.spec.hostIPC == null) or (.spec.hostIPC == false))' | jq .metadata.name | wc -l | xargs -I {} echo '--count={}'

Expected result:

1 is greater than 0

5.2.4 Minimize the admission of containers wishing to share the host network namespace (Scored)

Result: PASS

Remediation: Create a PSP as described in the Kubernetes documentation, ensuring that the .spec.hostNetwork field is omitted or set to false.

Audit:

kubectl --kubeconfig=/root/.kube/config get psp -o json | jq .items[] | jq -r 'select((.spec.hostNetwork == null) or (.spec.hostNetwork == false))' | jq .metadata.name | wc -l | xargs -I {} echo '--count={}'

Expected result:

1 is greater than 0

5.2.5 Minimize the admission of containers with allowPrivilegeEscalation (Scored)

Result: PASS

Remediation: Create a PSP as described in the Kubernetes documentation, ensuring that the .spec.allowPrivilegeEscalation field is omitted or set to false.

Audit:

kubectl --kubeconfig=/root/.kube/config get psp -o json | jq .items[] | jq -r 'select((.spec.allowPrivilegeEscalation == null) or (.spec.allowPrivilegeEscalation == false))' | jq .metadata.name | wc -l | xargs -I {} echo '--count={}'

Expected result:

1 is greater than 0

5.3 Network Policies and CNI

5.3.2 Ensure that all Namespaces have Network Policies defined (Scored)

Result: PASS

Remediation: Follow the documentation and create NetworkPolicy objects as you need them.

Audit Script: 5.3.2.sh

#!/bin/bash -e

export KUBECONFIG=${KUBECONFIG:-"/root/.kube/config"}

kubectl version > /dev/null
if [ $? -ne 0 ]; then
  echo "fail: kubectl failed"
  exit 1
fi

for namespace in $(kubectl get namespaces -A -o json | jq -r '.items[].metadata.name'); do
  policy_count=$(kubectl get networkpolicy -n ${namespace} -o json | jq '.items | length')
  if [ ${policy_count} -eq 0 ]; then
    echo "fail: ${namespace}"
    exit 1
  fi
done

echo "pass"

Audit Execution:

./5.3.2.sh 

Expected result:

'pass' is present

5.6 General Policies

5.6.4 The default namespace should not be used (Scored)

Result: PASS

Remediation: Ensure that namespaces are created to allow for appropriate segregation of Kubernetes resources and that all new resources are created in a specific namespace.

Audit Script: 5.6.4.sh

#!/bin/bash -e

export KUBECONFIG=${KUBECONFIG:-/root/.kube/config}

kubectl version > /dev/null
if [[ $? -gt 0 ]]; then
  echo "fail: kubectl failed"
  exit 1
fi

default_resources=$(kubectl get all -o json | jq --compact-output '.items[] | select((.kind == "Service") and (.metadata.name == "kubernetes") and (.metadata.namespace == "default") | not)' | wc -l)

echo "--count=${default_resources}"

Audit Execution:

./5.6.4.sh 

Expected result:

'0' is equal to '0'