---
controls:
version: "k3s-cis-1.24"
id: 4
text: "Worker Node Security Configuration"
type: "node"
groups:
  - id: 4.1
    text: "Worker Node Configuration Files"
    checks:
      - id: 4.1.1
        text: "Ensure that the kubelet service file permissions are set to 600 or more restrictive (Automated)"
        audit: '/bin/sh -c ''if test -e $kubeletsvc; then stat -c permissions=%a $kubeletsvc; fi'' '
        type: "skip"
        tests:
          test_items:
            - flag: "permissions"
              compare:
                op: bitmask
                value: "600"
        remediation: |
          Not Applicable.
          The kubelet is embedded in the k3s process. There is no kubelet service file, all configuration is passed in as arguments at runtime.
        scored: true

      - id: 4.1.2
        text: "Ensure that the kubelet service file ownership is set to root:root (Automated)"
        audit: '/bin/sh -c ''if test -e $kubeletsvc; then stat -c %U:%G $kubeletsvc; fi'' '
        type: "skip"
        tests:
          test_items:
            - flag: root:root
        remediation: |
          Not Applicable.
          The kubelet is embedded in the k3s process. There is no kubelet service file, all configuration is passed in as arguments at runtime.
        scored: true

      - id: 4.1.3
        text: "If proxy kubeconfig file exists ensure permissions are set to 600 or more restrictive (Automated)"
        audit: '/bin/sh -c ''if test -e $proxykubeconfig; then stat -c permissions=%a $proxykubeconfig; fi'' '
        tests:
          bin_op: or
          test_items:
            - flag: "permissions"
              set: true
              compare:
                op: bitmask
                value: "600"
        remediation: |
          Run the below command (based on the file location on your system) on the each worker node.
          For example,
          chmod 600 $proxykubeconfig
        scored: true

      - id: 4.1.4
        text: "If proxy kubeconfig file exists ensure ownership is set to root:root (Automated)"
        audit: 'stat -c %U:%G $proxykubeconfig'
        tests:
          bin_op: or
          test_items:
            - flag: root:root
        remediation: |
          Run the below command (based on the file location on your system) on the each worker node.
          For example, chown root:root $proxykubeconfig
        scored: true

      - id: 4.1.5
        text: "Ensure that the --kubeconfig kubelet.conf file permissions are set to 600 or more restrictive (Automated)"
        audit: '/bin/sh -c ''if test -e $kubeletkubeconfig; then stat -c permissions=%a $kubeletkubeconfig; fi'' '
        tests:
          test_items:
            - flag: "permissions"
              compare:
                op: bitmask
                value: "600"
        remediation: |
          Run the below command (based on the file location on your system) on the each worker node.
          For example,
          chmod 600 $kubeletkubeconfig
        scored: true

      - id: 4.1.6
        text: "Ensure that the --kubeconfig kubelet.conf file ownership is set to root:root (Automated)"
        audit: 'stat -c %U:%G $kubeletkubeconfig'
        tests:
          test_items:
            - flag: "root:root"
              compare:
                op: eq
                value: "root:root"
              set: true
        remediation: |
          Run the below command (based on the file location on your system) on the each worker node.
          For example,
          chown root:root $kubeletkubeconfig
        scored: true

      - id: 4.1.7
        text: "Ensure that the certificate authorities file permissions are set to 600 or more restrictive (Automated)"
        audit: "stat -c permissions=%a $kubeletcafile"
        tests:
          test_items:
            - flag: "permissions"
              compare:
                op: bitmask
                value: "600"
              set: true
        remediation: |
          Run the following command to modify the file permissions of the
          --client-ca-file chmod 600 $kubeletcafile
        scored: true

      - id: 4.1.8
        text: "Ensure that the client certificate authorities file ownership is set to root:root (Automated)"
        audit: "stat -c %U:%G $kubeletcafile"
        tests:
          test_items:
            - flag: root:root
              compare:
                op: eq
                value: root:root
        remediation: |
          Run the following command to modify the ownership of the --client-ca-file.
          chown root:root $kubeletcafile
        scored: true

      - id: 4.1.9
        text: "If the kubelet config.yaml configuration file is being used validate permissions set to 600 or more restrictive (Automated)"
        audit: '/bin/sh -c ''if test -e $kubeletconf; then stat -c permissions=%a $kubeletconf; fi'' '
        type: "skip"
        tests:
          test_items:
            - flag: "permissions"
              compare:
                op: bitmask
                value: "600"
        remediation: |
          Not Applicable.
          The kubelet is embedded in the k3s process. There is no kubelet config file, all configuration is passed in as arguments at runtime.
        scored: true

      - id: 4.1.10
        text: "If the kubelet config.yaml configuration file is being used validate file ownership is set to root:root (Automated)"
        audit: '/bin/sh -c ''if test -e $kubeletconf; then stat -c %U:%G $kubeletconf; fi'' '
        type: "skip"
        tests:
          test_items:
            - flag: root:root
        remediation: |
          Not Applicable.
          The kubelet is embedded in the k3s process. There is no kubelet config file, all configuration is passed in as arguments at runtime.
        scored: true

  - id: 4.2
    text: "Kubelet"
    checks:
      - id: 4.2.1
        text: "Ensure that the --anonymous-auth argument is set to false (Automated)"
        audit: '/bin/sh -c ''if test $(journalctl -m -u k3s -u k3s-agent | grep "Running kubelet" | wc -l) -gt 0; then journalctl -m -u k3s -u k3s-agent | grep "Running kubelet" | tail -n1 | grep "anonymous-auth" | grep -v grep; else echo "--anonymous-auth=false"; fi'' '
        tests:
          test_items:
            - flag: "--anonymous-auth"
              path: '{.authentication.anonymous.enabled}'
              compare:
                op: eq
                value: false
              set: true
        remediation: |
          By default, K3s sets the --anonymous-auth to false. If you have set this to a different value, you
          should set it back to false. If using the K3s config file /etc/rancher/k3s/config.yaml, remove any lines similar to below.
          kubelet-arg:
            - "anonymous-auth=true"
          If using the command line, edit the K3s service file and remove the below argument.
          --kubelet-arg="anonymous-auth=true"
          Based on your system, restart the k3s service. For example,
          systemctl daemon-reload
          systemctl restart k3s.service
        scored: true

      - id: 4.2.2
        text: "Ensure that the --authorization-mode argument is not set to AlwaysAllow (Automated)"
        audit: '/bin/sh -c ''if test $(journalctl -m -u k3s -u k3s-agent | grep "Running kubelet" | wc -l) -gt 0; then journalctl -m -u k3s -u k3s-agent | grep "Running kubelet" | tail -n1 | grep "authorization-mode"; else echo "--authorization-mode=Webhook"; fi'' '
        tests:
          test_items:
            - flag: --authorization-mode
              path: '{.authorization.mode}'
              compare:
                op: nothave
                value: AlwaysAllow
              set: true
        remediation: |
          By default, K3s does not set the --authorization-mode to AlwaysAllow.
          If using the K3s config file /etc/rancher/k3s/config.yaml, remove any lines similar to below.
          kubelet-arg:
            - "authorization-mode=AlwaysAllow"
          If using the command line, edit the K3s service file and remove the below argument.
          --kubelet-arg="authorization-mode=AlwaysAllow"
          Based on your system, restart the k3s service. For example,
          systemctl daemon-reload
          systemctl restart k3s.service
        scored: true

      - id: 4.2.3
        text: "Ensure that the --client-ca-file argument is set as appropriate (Automated)"
        audit: '/bin/sh -c ''if test $(journalctl -m -u k3s -u k3s-agent | grep "Running kubelet" | wc -l) -gt 0; then journalctl -m -u k3s -u k3s-agent | grep "Running kubelet" | tail -n1 | grep "client-ca-file"; else echo "--client-ca-file=/var/lib/rancher/k3s/server/tls/request-header-ca.crt"; fi'' '
        tests:
          test_items:
            - flag: --client-ca-file
              path: '{.authentication.x509.clientCAFile}'
              set: true
        remediation: |
          By default, K3s automatically provides the client ca certificate for the Kubelet.
          It is generated and located at /var/lib/rancher/k3s/agent/client-ca.crt
        scored: true

      - id: 4.2.4
        text: "Verify that the --read-only-port argument is set to 0 (Automated)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        tests:
          bin_op: or
          test_items:
            - flag: "--read-only-port"
              path: '{.readOnlyPort}'
              compare:
                op: eq
                value: 0
            - flag: "--read-only-port"
              path: '{.readOnlyPort}'
              set: false
        remediation: |
          By default, K3s sets the --read-only-port to 0. If you have set this to a different value, you
          should set it back to 0. If using the K3s config file /etc/rancher/k3s/config.yaml, remove any lines similar to below.
          kubelet-arg:
            - "read-only-port=XXXX"
          If using the command line, edit the K3s service file and remove the below argument.
          --kubelet-arg="read-only-port=XXXX"
          Based on your system, restart the k3s service. For example,
          systemctl daemon-reload
          systemctl restart k3s.service
        scored: true

      - id: 4.2.5
        text: "Ensure that the --streaming-connection-idle-timeout argument is not set to 0 (Manual)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        tests:
          test_items:
            - flag: --streaming-connection-idle-timeout
              path: '{.streamingConnectionIdleTimeout}'
              compare:
                op: noteq
                value: 0
            - flag: --streaming-connection-idle-timeout
              path: '{.streamingConnectionIdleTimeout}'
              set: false
          bin_op: or
        remediation: |
          If using the K3s config file /etc/rancher/k3s/config.yaml, set the following parameter to an appropriate value.
          kubelet-arg:
            - "streaming-connection-idle-timeout=5m"
          If using the command line, run K3s with --kubelet-arg="streaming-connection-idle-timeout=5m".
          Based on your system, restart the k3s service. For example,
          systemctl restart k3s.service
        scored: false

      - id: 4.2.6
        text: "Ensure that the --protect-kernel-defaults argument is set to true (Automated)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        tests:
          test_items:
            - flag: --protect-kernel-defaults
              path: '{.protectKernelDefaults}'
              compare:
                op: eq
                value: true
              set: true
        remediation: |
          If using the K3s config file /etc/rancher/k3s/config.yaml, set the following parameter.
          protect-kernel-defaults: true
          If using the command line, run K3s with --protect-kernel-defaults=true.
          Based on your system, restart the k3s service. For example,
          systemctl restart k3s.service
        scored: true

      - id: 4.2.7
        text: "Ensure that the --make-iptables-util-chains argument is set to true (Automated)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        tests:
          test_items:
            - flag: --make-iptables-util-chains
              path: '{.makeIPTablesUtilChains}'
              compare:
                op: eq
                value: true
              set: true
            - flag: --make-iptables-util-chains
              path: '{.makeIPTablesUtilChains}'
              set: false
          bin_op: or
        remediation: |
          If using the K3s config file /etc/rancher/k3s/config.yaml, set the following parameter.
          kubelet-arg:
            - "make-iptables-util-chains=true"
          If using the command line, run K3s with --kubelet-arg="make-iptables-util-chains=true".
          Based on your system, restart the k3s service. For example,
          systemctl restart k3s.service
        scored: true

      - id: 4.2.8
        text: "Ensure that the --hostname-override argument is not set (Automated)"
        type: "skip"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        tests:
          test_items:
            - flag: --hostname-override
              set: false
        remediation: |
          Not Applicable.
          By default, K3s does set the --hostname-override argument. Per CIS guidelines, this is to comply
          with cloud providers that require this flag to ensure that hostname matches node names.
        scored: true

      - id: 4.2.9
        text: "Ensure that the eventRecordQPS argument is set to a level which ensures appropriate event capture (Manual)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        audit_config: "/bin/cat $kubeletconf"
        tests:
          test_items:
            - flag: --event-qps
              path: '{.eventRecordQPS}'
              compare:
                op: eq
                value: 0
        remediation: |
          By default, K3s sets the event-qps to 0. Should you wish to change this,
          If using the K3s config file /etc/rancher/k3s/config.yaml, set the following parameter to an appropriate value.
          kubelet-arg:
            - "event-qps=<value>"
          If using the command line, run K3s with --kubelet-arg="event-qps=<value>".
          Based on your system, restart the k3s service. For example,
          systemctl restart k3s.service
        scored: false

      - id: 4.2.10
        text: "Ensure that the --tls-cert-file and --tls-private-key-file arguments are set as appropriate (Automated)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        tests:
          test_items:
            - flag: --tls-cert-file
              path: '/var/lib/rancher/k3s/agent/serving-kubelet.crt'
            - flag: --tls-private-key-file
              path: '/var/lib/rancher/k3s/agent/serving-kubelet.key'
        remediation: |
          By default, K3s automatically provides the TLS certificate and private key for the Kubelet.
          They are generated and located at /var/lib/rancher/k3s/agent/serving-kubelet.crt and /var/lib/rancher/k3s/agent/serving-kubelet.key
          If for some reason you need to provide your own certificate and key, you can set the
          below parameters in the K3s config file /etc/rancher/k3s/config.yaml.
          kubelet-arg:
            - "tls-cert-file=<path/to/tls-cert-file>"
            - "tls-private-key-file=<path/to/tls-private-key-file>"
        scored: true

      - id: 4.2.11
        text: "Ensure that the --rotate-certificates argument is not set to false (Automated)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        audit_config: "/bin/sh -c 'if test -e $kubeletconf; then /bin/cat $kubeletconf; fi' "
        tests:
          test_items:
            - flag: --rotate-certificates
              path: '{.rotateCertificates}'
              compare:
                op: eq
                value: true
            - flag: --rotate-certificates
              path: '{.rotateCertificates}'
              set: false
          bin_op: or
        remediation: |
          By default, K3s does not set the --rotate-certificates argument. If you have set this flag with a value of `false`, you should either set it to `true` or completely remove the flag.
          If using the K3s config file /etc/rancher/k3s/config.yaml, remove any rotate-certificates parameter.
          If using the command line, remove the K3s flag --kubelet-arg="rotate-certificates".
          Based on your system, restart the k3s service. For example,
          systemctl restart k3s.service
        scored: true

      - id: 4.2.12
        text: "Verify that the RotateKubeletServerCertificate argument is set to true (Automated)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        tests:
          bin_op: or
          test_items:
            - flag: RotateKubeletServerCertificate
              path: '{.featureGates.RotateKubeletServerCertificate}'
              compare:
                op: nothave
                value: false
            - flag: RotateKubeletServerCertificate
              path: '{.featureGates.RotateKubeletServerCertificate}'
              set: false
        remediation: |
          By default, K3s does not set the RotateKubeletServerCertificate feature gate.
          If you have enabled this feature gate, you should remove it.
          If using the K3s config file /etc/rancher/k3s/config.yaml, remove any feature-gate=RotateKubeletServerCertificate parameter.
          If using the command line, remove the K3s flag --kubelet-arg="feature-gate=RotateKubeletServerCertificate".
          Based on your system, restart the k3s service. For example,
          systemctl restart k3s.service
        scored: true

      - id: 4.2.13
        text: "Ensure that the Kubelet only makes use of Strong Cryptographic Ciphers (Manual)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        audit_config: "/bin/cat $kubeletconf"
        tests:
          test_items:
            - flag: --tls-cipher-suites
              path: '{range .tlsCipherSuites[:]}{}{'',''}{end}'
              compare:
                op: valid_elements
                value: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,TLS_RSA_WITH_AES_256_GCM_SHA384,TLS_RSA_WITH_AES_128_GCM_SHA256
        remediation: |
          If using a K3s config file /etc/rancher/k3s/config.yaml, edit the file to set `tlsCipherSuites` to
          kubelet-arg:
            - "tls-cipher-suites=TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305"
          or to a subset of these values.
          If using the command line, add the K3s flag --kubelet-arg="tls-cipher-suites=<same values as above>"
          Based on your system, restart the k3s service. For example,
          systemctl restart k3s.service
        scored: false
