kube-bench/cfg/k3s-cis-1.7/node.yaml

---
controls:
version: "k3s-cis-1.7"
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)"
        type: "skip"
        audit: '/bin/sh -c ''if test -e $kubeletsvc; then stat -c permissions=%a $kubeletsvc; fi'' '
        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)"
        type: "skip"
        audit: '/bin/sh -c ''if test -e $kubeletsvc; then stat -c %U:%G $kubeletsvc; fi'' '
        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.
          Not Applicable.
           All configuration is passed in as arguments at container run time.          
        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"
              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: '/bin/sh -c ''if test -e $proxykubeconfig; then stat -c %U:%G $proxykubeconfig; fi'' '
        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
        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"
        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: "Ensure that the kubelet --config configuration file has permissions set to 600 or more restrictive (Automated)"
        type: "skip"
        audit: '/bin/sh -c ''if test -e $kubeletconf; then stat -c permissions=%a $kubeletconf; fi'' '
        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: "Ensure that the kubelet --config configuration file ownership is set to root:root (Automated)"
        type: "skip"
        audit: '/bin/sh -c ''if test -e $kubeletconf; then stat -c %U:%G $kubeletconf; fi'' '
        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 | 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
        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'' '
        audit_config: "/bin/sh -c 'if test -e $kubeletconf; then /bin/cat $kubeletconf; fi' "
        tests:
          test_items:
            - flag: --authorization-mode
              path: '{.authorization.mode}'
              compare:
                op: nothave
                value: AlwaysAllow
        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}'
        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"
        audit_config: "/bin/sh -c 'if test -e $kubeletconf; then /bin/cat $kubeletconf; fi' "
        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 --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
            - 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: 4.2.7
        text: "Ensure that the --hostname-override argument is not set (Automated)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        type: "skip"
        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: 4.2.8
        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/sh -c 'if test -e $kubeletconf; then /bin/cat $kubeletconf; fi' "
        tests:
          test_items:
            - flag: --event-qps
              path: '{.eventRecordQPS}'
              compare:
                op: gte
                value: 0
            - flag: --event-qps
              path: '{.eventRecordQPS}'
              set: false
          bin_op: or
        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: 4.2.9
        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
         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: 4.2.10
        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: 4.2.11
        text: "Verify that the RotateKubeletServerCertificate argument is set to true (Automated)"
        audit: "journalctl -m -u k3s -u k3s-agent | grep 'Running kubelet' | tail -n1"
        audit_config: "/bin/cat $kubeletconf"
        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: 4.2.12
        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/sh -c 'if test -e $kubeletconf; then /bin/cat $kubeletconf; fi' "
        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

      - id: 4.2.13
        text: "Ensure that a limit is set on pod PIDs (Manual)"
        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: --pod-max-pids
              path: '{.podPidsLimit}'
        remediation: |
          Decide on an appropriate level for this parameter and set it,
          If using a K3s config file /etc/rancher/k3s/config.yaml, edit the file to set `podPidsLimit` to
          kubelet-arg:
            - "pod-max-pids=<value>"          
        scored: false