CIS Kubernetes Benchmark 1.3.0 - Rancher 2.1.x with Kubernetes 1.11

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Overview

The following document scores a Kubernetes 1.11.x RKE cluster provisioned according to the Rancher v2.1.x hardening guide against the CIS 1.3.0 Kubernetes benchmark.

This document is a companion to the Rancher v2.1.x 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.

Because Rancher and RKE install Kubernetes services as Docker containers, many of the control verification checks in the CIS Kubernetes Benchmark don’t apply. 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 v1.3.0. 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.

Scoring the commands is different in Rancher Labs than in the CIS Benchmark. Where the commands differ from the original CIS benchmark, the 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 command to provide human-readable formatting.

Tests will have an exit code of zero on success and non-zero on failure.

Known Scored Control Failures

The following scored controls do not currently pass, and Rancher Labs is working towards addressing these through future enhancements to the product.

  • 1.1.21 - Ensure that the --kubelet-certificate-authority argument is set as appropriate (Scored)
  • 1.3.6 - Ensure that the RotateKubeletServerCertificate argument is set to true (Scored)
  • 1.4.11 - Ensure that the etcd data directory permissions are set to 700 or more-restrictive (Scored)
  • 1.4.12 - Ensure that the etcd data directory ownership is set to etcd:etcd (Scored)
  • 2.1.3 - Ensure that the --authorization-mode argument is not set to AlwaysAllow (Scored)
  • 2.1.9 - Ensure that the --hostname-override argument is not set (Scored)
  • 2.1.13 - Ensure that the --rotate-certificates argument is not set to false (Scored)
  • 2.1.14 - Ensure that the RotateKubeletServerCertificate argument is set to true (Scored)

Controls

1 - Master Node Security Configuration

1.1 - API Server

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--anonymous-auth=false").string'

Returned Value: --anonymous-auth=false

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--basic-auth-file=.*").string'

Returned Value: null

Result: Pass

1.1.3 - Ensure that the --insecure-allow-any-token argument is not set (Scored)

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--insecure-allow-any-token").string'

Returned Value: null

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--kubelet-https=false").string'

Returned Value: null

Result: Pass

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

Notes

Flag not set or --insecure-bind-address=127.0.0.1. RKE sets this flag to --insecure-bind-address=127.0.0.1

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--insecure-bind-address=(?:(?!127\\.0\\.0\\.1).)+")'

Returned Value: null

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--insecure-port=0").string'

Returned Value: --insecure-port=0

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--secure-port=6443").string'

Returned Value: --secure-port=6443

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--profiling=false").string'

Returned Value: --profiling=false

Result: Pass

1.1.9 - Ensure that the --repair-malformed-updates argument is set to false (Scored)

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--repair-malformed-updates=false").string'

Returned Value: --repair-malformed-updates=false

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(AlwaysAdmit).*").captures[].string'

Returned Value: null

Result: Pass

1.1.11 - Ensure that the admission control plugin AlwaysPullImages is set (Scored)

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(AlwaysPullImages).*").captures[].string'

Returned Value: AlwaysPullImages

Result: Pass

1.1.12 - Ensure that the admission control plugin DenyEscalatingExec is set (Scored)

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(DenyEscalatingExec).*").captures[].string'

Returned Value: DenyEscalatingExec

Result: Pass

1.1.13 - Ensure that the admission control plugin SecurityContextDeny is set (Scored)

Notes

This control may be out of date. This SHOULD NOT be set if you are using a PodSecurityPolicy (PSP). From the Kubernetes 1.11 documentation:

This should be enabled if a cluster doesn’t utilize pod security policies to restrict the set of values a security context can take.

Several system services (such as nginx-ingress) utilize SecurityContext to switch users and assign capabilities. These exceptions to the general principle of not allowing privilege or capabilities can be managed with PSP.

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(SecurityContextDeny).*").captures[].string'

Returned Value: null

Result: Document

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(NamespaceLifecycle).*").captures[].string'

Returned Value: NamespaceLifecycle

Result: Pass

1.1.15 - Ensure that the --audit-log-path argument is set as appropriate (Scored)

Notes

This path is the path inside of the container. It’s combined with the RKE cluster.yml extra-binds: option to map the audit log to the host filesystem.

Audit logs should be collected and shipped off-system to guarantee their integrity.

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--audit-log-path=/var/log/kube-audit/audit-log.json").string'

Returned Value: --audit-log-log=/var/log/kube-audit/audit-log.json

Result: Pass

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

Notes

Audit logs should be collected and shipped off-system to guarantee their integrity. Rancher Labs recommends setting this argument to a low value to prevent audit logs from filling the local disk.

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--audit-log-maxage=\\d+").string'

Returned Value: --audit-log-maxage=5

Result: Pass

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

Notes

Audit logs should be collected and shipped off-system to guarantee their integrity. Rancher Labs recommends setting this argument to a low value to prevent audit logs from filling the local disk.

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--audit-log-maxbackup=\\d+").string'

Returned Value: --audit-log-maxbackup=5

Result: Pass

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

Notes

Audit logs should be collected and shipped off-system to guarantee their integrity.

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--audit-log-maxsize=\\d+").string'

Returned Value: --audit-log-maxsize=100

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--authorization-mode=(Node|RBAC|,)+").string'

Returned Value: --authorization-mode=Node,RBAC

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--token-auth-file=.*").string'

Returned Value: null

Result: Pass

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

Notes

RKE is using the kubelet’s ability to automatically create self-signed certs. No CA cert is saved to verify the communication between kube-apiserver and kubelet.

Mitigation

Make sure nodes with role:controlplane are on the same local network as your nodes with role:worker. Use network ACLs to restrict connections to the kubelet port (10250/tcp) on worker nodes, only permitting it from controlplane nodes.

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--kubelet-certificate-authority=.*").string'

Returned Value: none

Result: Fail (See Mitigation)

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

Audit (--kubelet-client-certificate)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--kubelet-client-certificate=.*").string'

Returned Value: --kubelet-client-certificate=/etc/kubernetes/ssl/kube-apiserver.pem

Audit (--kubelet-client-key)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--kubelet-client-key=.*").string'

Returned Value: --kubelet-client-key=/etc/kubernetes/ssl/kube-apiserver-key.pem

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--service-account-lookup=true").string'

Returned Value: --service-account-lookup=true

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(PodSecurityPolicy).*").captures[].string'

Returned Value: PodSecurityPolicy

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--service-account-key-file=.*").string'

Returned Value: --service-account-key-file=/etc/kubernetes/ssl/kube-apiserver-key.pem

Result: Pass

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

Audit (--etcd-certfile)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--etcd-certfile=.*").string'

Returned Value: --etcd-certfile=/etc/kubernetes/ssl/kube-node.pem

Audit (--etcd-keyfile)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--etcd-keyfile=.*").string'

Returned Value: --etcd-keyfile=/etc/kubernetes/ssl/kube-node-key.pem

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(ServiceAccount).*").captures[].string'

Returned Value: ServiceAccount

Result: Pass

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

Audit (--tls-cert-file)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cert-file=.*").string'

Returned Value: --tls-cert-file=/etc/kubernetes/ssl/kube-apiserver.pem

Audit (--tls-key-file)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-private-key-file=.*").string'

Returned Value: --tls-private-key-file=/etc/kubernetes/ssl/kube-apiserver-key.pem

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--client-ca-file=.*").string'

Returned Value: --client-ca-file=/etc/kubernetes/ssl/kube-ca.pem Result: Pass

1.1.30 - Ensure that the API Server only makes use of strong cryptographic ciphers (Not Scored)

Audit (Allowed Ciphers)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value: The return should be blank.

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value: The return should be blank.

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305).*").captures[].string'

Returned Value: The return should be blank.

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_RSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_RSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value: TLS_RSA_WITH_AES_256_GCM_SHA384

Audit (Disallowed Ciphers)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(CBC).*").captures[].string'

Returned Value: null

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(RC4).*").captures[].string'

Returned Value: null

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--etcd-cafile=.*").string'

Returned Value: --etcd-cafile=/etc/kubernetes/ssl/kube-ca.pem

Result: Pass

1.1.32 - Ensure that the --authorization-mode argument is set to Node (Scored)

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--authorization-mode=(Node|RBAC|,)+").string'

Returned Value: --authorization-mode=Node,RBA Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(NodeRestriction).*").captures[].string'

Returned Value: NodeRestriction

Result: Pass

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

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--experimental-encryption-provider-config=.*").string'

Returned Value: --experimental-encryption-provider-config=/etc/kubernetes/encryption.yaml

Result: Pass

1.1.35 - Ensure that the encryption provider is set to aescbc (Scored)

Notes

Only the first provider in the list is active.

Audit

grep -A 1 providers: /etc/kubernetes/encryption.yaml | grep aescbc

Returned Value: - aescbc:

Result: Pass

1.1.36 - Ensure that the admission control plugin EventRateLimit is set (Scored)

Notes

The EventRateLimit plugin requires setting the --admission-control-config-file option and configuring details in the following files:

  • /etc/kubernetes/admission.yaml
  • /etc/kubernetes/event.yaml

See Host Configuration for details.

Audit (Admissions plugin)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--enable-admission-plugins=.*(EventRateLimit).*").captures[].string'

Returned Value: EventRateLimit

Audit (--admission-control-config-file)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--admission-control-config-file=.*").string'

Returned Value: --admission-control-config-file=/etc/kubernetes/admission.yaml

Result: Pass

1.1.37 Ensure that the AdvancedAuditing argument is not set to false (Scored)

Notes

AdvancedAuditing=false should not be set, but --audit-policy-file should be set and configured. See Host Configuration for a sample audit policy file.

Audit (Feature Gate)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--feature-gates=.*(AdvancedAuditing=false).*").captures[].string'

Returned Value: null

Audit (Audit Policy File)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--audit-policy-file=.*").string'

Returned Value: --audit-policy-file=/etc/kubernetes/audit.yaml

Result: Pass

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

Notes

RKE uses the default value of 60s and doesn’t set this option.

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--request-timeout=.*").string'

Returned Value: null

Result: Pass

1.1.39 - Ensure that the API Server only makes use of strong cryptographic ciphers (Not Scored)

Notes

This appears to be a repeat of 1.1.30.

Audit (Allowed Ciphers)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value:

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value:

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305).*").captures[].string'

Returned Value:

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_RSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_RSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value: TLS_RSA_WITH_AES_256_GCM_SHA384

Audit (Disallowed Ciphers)

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(CBC).*").captures[].string'

Returned Value: null

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(RC4).*").captures[].string'

Returned Value: null

Result: Pass

1.2 - Scheduler

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

Audit

docker inspect kube-scheduler | jq -e '.[0].Args[] | match("--profiling=false").string'

Returned Value: --profiling=false Result: Pass

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

Audit

docker inspect kube-scheduler | jq -e '.[0].Args[] | match("--address=127\\.0\\.0\\.1").string'

Returned Value: --address=127.0.0.1 Result: Pass

1.3 - Controller Manager

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

Audit

docker inspect kube-controller-manager | jq -e '.[0].Args[] | match("--terminated-pod-gc-threshold=\\d+").string'

Returned Value: --terminated-pod-gc-threshold=1000 Result: Pass

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

Audit

docker inspect kube-controller-manager | jq -e '.[0].Args[] | match("--profiling=false").string'

Returned Value: --profiling=false

Result: Pass

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

Audit

docker inspect kube-controller-manager | jq -e '.[0].Args[] | match("--use-service-account-credentials=true").string'

Returned Value: --use-service-account-credentials=true

Result: Pass

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

Audit

docker inspect kube-controller-manager | jq -e '.[0].Args[] | match("--service-account-private-key-file=.*").string'

Returned Value: --service-account-private-key-file=/etc/kubernetes/ssl/kube-apiserver-key.pem

Result: Pass

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

Audit

docker inspect kube-controller-manager | jq -e '.[0].Args[] | match("--root-ca-file=.*").string'

Returned Value: --root-ca-file=/etc/kubernetes/ssl/kube-ca.pem

Result: Pass

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

Notes

RKE does not yet support certificate rotation. This feature is due for the 0.1.12 release of RKE.

Audit

docker inspect kube-apiserver | jq -e '.[0].Args[] | match("--feature-gates=.*(RotateKubeletServerCertificate=true).*").captures[].string'

Returned Value: null

Result: Fail

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

Audit

docker inspect kube-controller-manager | jq -e '.[0].Args[] | match("--address=127\\.0\\.0\\.1").string'

Returned Value: --address=127.0.0.1

Result: Pass

1.4 - Configuration Files

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

Notes

RKE doesn’t require or maintain a configuration file for kube-apiserver. All configuration is passed in as arguments at container run time.

Result: Pass (Not Applicable)

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

Notes

RKE doesn’t require or maintain a configuration file for kube-apiserver. All configuration is passed in as arguments at container run time.

Result: Pass (Not Applicable)

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

Notes

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

Result: Pass (Not Applicable)

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

Notes

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

Result: Pass (Not Applicable)

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

Notes

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

Result: Pass (Not Applicable)

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

Notes

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

Result: Pass (Not Applicable)

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

Notes

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

Result: Pass (Not Applicable)

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

Notes

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

Result: Pass (Not Applicable)

1.4.9 - Ensure that the Container Network Interface file permissions are set to 644 or more restrictive (Not Scored)

Notes

This is a manual check.

Audit (/var/lib/cni/networks/k8s-pod-network)

ls -l /var/lib/cni/networks/k8s-pod-network/

Returned Value:

-rw-r--r-- 1 root root   64 Nov  6 20:05 10.42.0.2
-rw-r--r-- 1 root root   64 Nov  6 20:05 10.42.0.3
-rw-r--r-- 1 root root   64 Nov  6 20:05 10.42.0.4
-rw-r--r-- 1 root root   64 Nov  6 20:05 10.42.0.5
-rw-r--r-- 1 root root   10 Nov  7 16:25 last_reserved_ip.0

Audit (/etc/cni/net.d)

ls -l /etc/cni/net.d/

Returned Value:

-rw-r--r-- 1 root root 1474 Nov  6 20:05 10-calico.conflist
-rw------- 1 root root 2529 Nov  6 20:05 calico-kubeconfig

Result: Pass

1.4.10 - Ensure that the Container Network Interface file ownership is set to root:root (Not Scored)

Notes

This is a manual check.

Audit (/var/lib/cni/networks/k8s-pod-network)

ls -l /var/lib/cni/networks/k8s-pod-network/

Returned Value:

-rw-r--r-- 1 root root   64 Nov  6 20:05 10.42.0.2
-rw-r--r-- 1 root root   64 Nov  6 20:05 10.42.0.3
-rw-r--r-- 1 root root   64 Nov  6 20:05 10.42.0.4
-rw-r--r-- 1 root root   64 Nov  6 20:05 10.42.0.5
-rw-r--r-- 1 root root   10 Nov  7 16:25 last_reserved_ip.0

Audit (/etc/cni/net.d)

ls -l /etc/cni/net.d/

Returned Value:

-rw-r--r-- 1 root root 1474 Nov  6 20:05 10-calico.conflist
-rw------- 1 root root 2529 Nov  6 20:05 calico-kubeconfig

Result: Pass

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

Notes

Files underneath the data dir are permissioned 700

ls -al /var/lib/etcd
total 12
drwxr-xr-x  3 root root 4096 Nov 14 17:06 .
drwxr-xr-x 47 root root 4096 Nov 14 17:06 ..
drwx------  4 root root 4096 Nov 14 17:06 member

Audit

stat -c %a /var/lib/etcd

Returned Value: 755

Result: Fail

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

Notes

The etcd container runs as the root user. The data directory and files are owned by root.

Audit

stat -c %U:%G /var/lib/etcd

Returned Value: root:root

Result: Fail

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

Notes

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.

Result: Pass (Not Applicable)

1.4.14 - Ensure that ownership of admin.conf is set to root:root (Scored)

Notes

RKE does not store the default kubectl config credentials file on the nodes. It presents credentials to the user when rke is first run, and only on the device where the user ran the command. Rancher Labs recommends that this kube_config_cluster.yml file be kept in secure store.

Result: Pass (Not Applicable)

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

Audit

stat -c %a /etc/kubernetes/ssl/kubecfg-kube-scheduler.yaml

Returned Value: 644

Result: Pass

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

Audit

stat -c %U:%G /etc/kubernetes/ssl/kubecfg-kube-scheduler.yaml

Returned Value: root:root

Result: Pass

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

Audit

stat -c %a /etc/kubernetes/ssl/kubecfg-kube-controller-manager.yaml

Returned Value: 644

Result: Pass

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

Audit

stat -c %U:%G /etc/kubernetes/ssl/kubecfg-kube-controller-manager.yaml

Returned Value: root:root

Result: Pass

1.5 - etcd

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

Audit (--cert-file)

docker inspect etcd | jq -e '.[0].Args[] | match("--cert-file=.*").string'

Returned Value: --cert-file=/etc/kubernetes/ssl/kube-etcd-172-31-22-135.pem

Audit (--key-file)

docker inspect etcd | jq -e '.[0].Args[] | match("--key-file=.*").string'

Returned Value: --key-file=/etc/kubernetes/ssl/kube-etcd-172-31-22-135-key.pem

Result: Pass

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

Notes

Setting “–client-cert-auth” is the equivalent of setting “–client-cert-auth=true”.

Audit

docker inspect etcd | jq -e '.[0].Args[] | match("--client-cert-auth(=true)*").string'

Returned Value: --client-cert-auth

Result: Pass

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

Audit

docker inspect etcd | jq -e '.[0].Args[] | match("--auto-tls(?:(?!=false).*)").string'

Returned Value: null

Result: Pass

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

Audit (--peer-cert-file)

docker inspect etcd | jq -e '.[0].Args[] | match("--peer-cert-file=.*").string'

Returned Value: --peer-cert-file=/etc/kubernetes/ssl/kube-etcd-172-31-22-135.pem

Audit (--peer-key-file)

docker inspect etcd | jq -e '.[0].Args[] | match("--peer-key-file=.*").string'

Returned Value: --peer-key-file=/etc/kubernetes/ssl/kube-etcd-172-31-22-135-key.pem

Result: Pass

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

Notes

Setting --peer-client-cert-auth is the equivalent of setting --peer-client-cert-auth=true.

Audit

docker inspect etcd | jq -e '.[0].Args[] | match("--peer-client-cert-auth(=true)*").string'

Returned Value: --client-cert-auth

Result: Pass

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

Audit

docker inspect etcd | jq -e '.[0].Args[] | match("--peer-auto-tls(?:(?!=false).*)").string'

Returned Value: null

Result: Pass

1.5.7 - Ensure that a unique Certificate Authority is used for etcd (Not Scored)

Notes

RKE does not currently implement a seperate CA for etcd certificates.

--trusted-ca-file is set and different from the --client-ca-file used by kube-apiserver.

Audit

docker inspect etcd | jq -e '.[0].Args[] | match("--trusted-ca-file=(?:(?!/etc/kubernetes/ssl/kube-ca.pem).*)").string'

Returned Value: null

Result: Fail

1.6 - General Security Primitives

These “Not Scored” controls are implementation best practices. To ease the administrative burden, we recommend that you implement these best practices on your workload clusters by creating clusters with Rancher rather than using RKE alone.

1.6.1 - Ensure that the cluster-admin role is only used where required (Not Scored)

Rancher has built in support for maintaining and enforcing Kubernetes RBAC on your workload clusters.

Rancher has the ability integrate with external authentication sources (LDAP, SAML, AD…) allows easy access with unique credentials to your existing users or groups.

1.6.2 - Create administrative boundaries between resources using namespaces (Not Scored)

With Rancher, users or groups can be assigned access to all clusters, a single cluster or a “Project” (a group of one or more namespaces in a cluster). This allows granular access control to cluster resources.

1.6.3 - Create network segmentation using Network Policies (Not Scored)

Rancher can (optionally) automatically create Network Policies to isolate “Projects” (a group of one or more namespaces) in a cluster.

See “Cluster Options” when creating a cluster with Rancher to turn on Network Isolation.

1.6.4 - Ensure that the seccomp profile is set to docker/default in your pod definitions (Not Scored)

Since this requires the enabling of AllAlpha feature gates we would not recommend enabling this feature at the moment.

1.6.5 - Apply security context to your pods and containers (Not Scored)

This practice does go against control 1.1.13, but we prefer using PodSecurityPolicy and allowing security context to be set over a blanket deny.

Rancher allows users to set various Security Context options when launching pods via the GUI interface.

1.6.6 - Configure image provenance using the ImagePolicyWebhook admission controller (Not Scored)

Image Policy Webhook requires a 3rd party service to enforce policy. This can be configured in the --admission-control-config-file. See the Host configuration section for the admission.yaml file.

1.6.7 - Configure network policies as appropriate (Not Scored)

Rancher can (optionally) automatically create Network Policies to isolate projects (a group of one or more namespaces) within a cluster.

See the Cluster Options section when creating a cluster with Rancher to turn on network isolation.

1.6.8 - Place compensating controls in the form of PodSecurityPolicy (PSP) and RBAC for privileged container usage (Not Scored)

Section 1.7 of this guide shows how to add and configure a default “restricted” PSP based on controls.

With Rancher you can create a centrally maintained “restricted” PSP and deploy it to all of the clusters that Rancher manages.

1.7 - Pod Security Policies (PSP)

This RKE configuration has two Pod Security Policies.

  • default-psp: assigned to namespaces that require additional privileged access: kube-system, ingress-nginx and cattle-system.
  • restricted: This is the cluster default PSP and follows the best practices defined by controls in this section.

1.7.1 - Do not admit privileged containers (Not Scored)

Notes

The restricted PodSecurityPolicy (PSP) is available to all ServiceAccounts.

Audit

kubectl get psp restricted -o jsonpath='{.spec.privileged}' | grep "true"

Returned Value: null

Result: Pass

1.7.2 - Do not admit containers wishing to share the host process ID namespace (Scored)

Notes

The restricted PodSecurityPolicy (PSP) is available to all ServiceAccounts.

Audit

kubectl get psp restricted -o jsonpath='{.spec.hostPID}' | grep "true"

Returned Value: null

Result: Pass

1.7.3 - Do not admit containers wishing to share the host IPC namespace (Scored)

Notes

The restricted PodSecurityPolicy (PSP) is available to all ServiceAccounts.

Audit

kubectl get psp restricted -o jsonpath='{.spec.hostIPC}' | grep "true"

Returned Value: null

Result: Pass

1.7.4 - Do not admit containers wishing to share the host network namespace (Scored)

Notes

The restricted PodSecurityPolicy (PSP) is available to all ServiceAccounts.

Audit

kubectl get psp restricted -o jsonpath='{.spec.hostNetwork}' | grep "true"

Returned Value: null

Result: Pass

1.7.5 - Do not admit containers with allowPrivilegeEscalation (Scored)

Notes

The restricted PodSecurityPolicy (PSP) is available to all ServiceAccounts.

Audit

kubectl get psp restricted -o jsonpath='{.spec.allowPrivilegeEscalation}' | grep "true"

Returned Value: null

Result: Pass

1.7.6 - Do not admit containers whose processes run as root (Not Scored)

Notes

The restricted PodSecurityPolicy (PSP) is available to all ServiceAccounts.

Audit

kubectl get psp restricted -o jsonpath='{.spec.runAsUser.rule}' | grep "RunAsAny"

Returned Value: null

Result: Pass

1.7.7 - Do not admit containers with dangerous capabilities (Not Scored)

Notes

The restricted PodSecurityPolicy (PSP) is available to all ServiceAccounts.

Audit

kubectl get psp restricted -o jsonpath='{.spec.requiredDropCapabilities}' | grep "NET_RAW"

Returned Value: [NET_RAW]

Result: Pass

2 - Worker Node Security Configuration

2.1 - Kubelet

2.1.1 - Ensure that the --allow-privileged argument is set to false (Scored)

Notes

The --allow-privileged argument is deprecated from Kubernetes v1.11, and the default setting is true with the intention that users should use PodSecurityPolicy settings to allow or prevent privileged containers.

Our RKE configuration uses PodSecurityPolicy with a default policy to reject privileged containers.

Result: Pass (Not Applicable)

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

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--anonymous-auth=false").string'

Returned Value: --anonymous-auth=false

Result: Pass

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

Notes

RKE currently runs the kubelet without the --authorization-mode flag.

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--authorization-mode=Webhook").string'

Returned Value: null

Result: Fail

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

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--client-ca-file=.*").string'

Returned Value: --client-ca-file=/etc/kubernetes/ssl/kube-ca.pem

Result: Pass

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

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--read-only-port=0").string'

Returned Value: --read-only-port=0

Result: Pass

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

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--streaming-connection-idle-timeout=.*").string'

Returned Value: --streaming-connection-idle-timeout=1800s

Result: Pass

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

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--protect-kernel-defaults=true").string'

Returned Value: --protect-kernel-defaults=true

Result: Pass

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

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--make-iptables-util-chains=true").string'

Returned Value: --make-iptables-util-chains=true

Result: Pass

2.1.9 - Ensure that the --hostname-override argument is not set (Scored)

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--hostname-override=.*").string'

Returned Value: --hostname-override=<ipv4 address>

Result: Fail

2.1.10 - Ensure that the --event-qps argument is set to 0 (Scored)

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--event-qps=0").string'

Returned Value: --event-qps=0

Result: Pass

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

Notes

RKE does not set these options and uses the kubelet’s self generated certificates for TLS communication. These files are located in the default directory (/var/lib/kubelet/pki).

Audit (--tls-cert-file)

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cert-file=.*").string'

Returned Value: null

Audit (--tls-private-key-file)

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-private-key-file=.*").string'

Returned Value: null

Result: Pass

2.1.12 - Ensure that the --cadvisor-port argument is set to 0 (Scored)

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--cadvisor-port=0").string'

Returned Value: --cadvisor-port=0

Result: Pass

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

Notes

RKE will enable certificate rotation in version 0.1.12.

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--rotate-certificates=true").string'

Returned Value: null

Result: Fail

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

Notes

RKE does not yet support certificate rotation. This feature is due for the 0.1.12 release of RKE.

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--feature-gates=.*(RotateKubeletServerCertificate=true).*").captures[].string'

Returned Value: null

Result: Fail

2.1.15 - Ensure that the kubelet only makes use of strong cryptographic ciphers (Not Scored)

Audit (Allowed Ciphers)

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value:

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value:

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305).*").captures[].string'

Returned Value:

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_RSA_WITH_AES_128_GCM_SHA256).*").captures[].string'

Returned Value: TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(TLS_RSA_WITH_AES_256_GCM_SHA384).*").captures[].string'

Returned Value: TLS_RSA_WITH_AES_256_GCM_SHA384

Audit (Disallowed Ciphers)

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(CBC).*").captures[].string'

Returned Value: null

Audit

docker inspect kubelet | jq -e '.[0].Args[] | match("--tls-cipher-suites=.*(RC4).*").captures[].string'

Returned Value: null

Result: Pass

2.2 - Configuration Files

2.2.1 - Ensure that the permissions for kubelet.conf are set to 644 or more restrictive (Scored)

Notes

This is the value of the --kubeconfig option.

Audit

stat -c %a /etc/kubernetes/ssl/kubecfg-kube-node.yaml

Returned Value: 644

Result: Pass

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

Notes

This is the value of the --kubeconfig option.

Audit

stat -c %U:%G /etc/kubernetes/ssl/kubecfg-kube-node.yaml

Returned Value: root:root

Result: Pass

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

Notes

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

Result: Pass (Not Applicable)

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

Notes

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

Result: Pass (Not Applicable)

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

Audit

stat -c %a /etc/kubernetes/ssl/kubecfg-kube-proxy.yaml

Returned Value: 644

Result: Pass

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

Audit

stat -c %U:%G /etc/kubernetes/ssl/kubecfg-kube-proxy.yaml

Returned Value: root:root

Result: Pass

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

Audit

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

Returned Value: 644

Result: Pass

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

Audit

stat -c %U:%G /etc/kubernetes/ssl/kube-ca.pem

Returned Value: root:root

Result: Pass

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

Notes

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

Result: Pass (Not Applicable)

2.2.10 - Ensure that the kubelet configuration file permissions are set to 644 or more restrictive (Scored)

Notes

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

Result: Pass (Not Applicable)