Use MITRE policy constraints

Preview

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Policy Controller comes with a default library of constraint templates that can be used with the MITRE policy bundle to evaluate the compliance of your cluster resources against some aspects of the MITRE knowledge base of adversary tactics and techniques based on real-world observations.

MITRE policy bundle constraints

Constraint Name	Constraint Description
mitre-v2024-apparmor	Restricts the AppArmor profile for Pods.
mitre-v2024-block-all-ingress	Restricts the creation of Ingress objects.
mitre-v2024-cronjob-restrict-repos	Restricts container images for CronJob to an allowed `repos` list.
mitre-v2024-no-anonymous	Disallows associating ClusterRole and Role resources to the system:anonymous user and system:unauthenticated group.
mitre-v2024-host-namespaces-host-pid-ipc	Containers cannot run with hostPID or hostIPC set to true.
mitre-v2024-host-namespaces-hostnetwork	Containers cannot run with hostNetwork set to true.
mitre-v2024-host-ports	HostPorts should be disallowed, or at minimum restricted to a known list.
mitre-v2024-no-secrets-as-env-vars	Restricts the use of secrets as environment variables in container definitions.
mitre-v2024-privileged-containers	Restricts containers with securityContext.privileged set to true.
mitre-v2024-proc-mount-type	The default /proc masks reduce attack surface, and are required.
mitre-v2024-require-binauthz	Requires the Binary Authorization Validating Admission Webhook.
mitre-v2024-require-namespace-networkpolicy	Requires that every namespace defined in the cluster has a NetworkPolicy.
mitre-v2024-restrict-admission-controller	Restricts the use of dynamic admission controllers and webhooks.
mitre-v2024-restrict-automountserviceaccounttoken	Restricts the use of service accounts tokens.
mitre-v2024-restrict-capabilities	Adding capabilities beyond those listed is not allowed.
mitre-v2024-restrict-cluster-admin-role	Restricts the use of the cluster-admin role.
mitre-v2024-restrict-hostpath-volumes	Restricts the use of HostPath volumes.
mitre-v2024-restrict-kubernetes-dashboard-namespace	Restricts the use of the kubernetes-dashboard namespace.
mitre-v2024-restrict-pods-exec	Restricts the use of pods/exec in Roles and ClusterRoles.
mitre-v2024-restrict-rbac-subjects	Restricts the use of names in RBAC subjects to permitted values.
mitre-v2024-restrict-repos	Restricts container images to an allowed repos list.
mitre-v2024-restrict-role-secrets	Restricts the use of secrets in Roles and ClusterRoles.
mitre-v2024-restrict-windows-hostprocess	Restricts running of Windows HostProcess containers / pods
mitre-v2024-seccomp	Seccomp profile must not be set to Unconfined.
mitre-v2024-selinux	Cannot set the SELinux type or set a custom SELinux user or role option.
mitre-v2024-sysctls	Containers can set only sysctls listed in the allowedSysctls field.

Before you begin

1. Install and initialize the Google Cloud CLI, which provides the gcloud and kubectl commands used in these instructions. If you use Cloud Shell, Google Cloud CLI comes pre-installed.
2. Install Policy Controller v1.17.2 or higher on your cluster with the default library of constraint templates. You must also enable support for referential constraints as this bundle contains referential constraints.

Configure Policy Controller for referential constraints

Warning: You can overwrite your changes. If you already have an existing Config in the gatekeeper-system namespace, you must include all previous customization settings to preserve your changes.

1. Save the following YAML manifest to a file as policycontroller-config.yaml. The manifest configures Policy Controller to watch specific kinds of objects.

   apiVersion: config.gatekeeper.sh/v1alpha1
   kind: Config
   metadata:
     name: config
     namespace: "gatekeeper-system"
   spec:
     sync:
       syncOnly:
         - group: "networking.k8s.io"
           version: "v1"
           kind: "NetworkPolicy"
         - group: "admissionregistration.k8s.io"
           version: "v1"
           kind: "ValidatingWebhookConfiguration"
   

2. Apply the policycontroller-config.yaml manifest:

   kubectl apply -f policycontroller-config.yaml
   

Audit MITRE policy bundle

Policy Controller lets you enforce policies for your Kubernetes cluster. To help test your workloads and their compliance with regard to the MITRE policies outlined in the preceding table, you can deploy these constraints in "audit" mode to reveal violations and more importantly give yourself a chance to fix them before enforcing on your Kubernetes cluster.

You can apply these policies with spec.enforcementAction set to dryrun using kubectl, kpt, or Config Sync.

kubectl

1. (Optional) Preview the policy constraints with kubectl:

   kubectl kustomize https://github.com/GoogleCloudPlatform/gke-policy-library.git/anthos-bundles/mitre-v2024
   

2. Apply the policy constraints with kubectl:

   kubectl apply -k https://github.com/GoogleCloudPlatform/gke-policy-library.git/anthos-bundles/mitre-v2024
   

   The output is the following:

   k8sallowedrepos.constraints.gatekeeper.sh/mitre-v2024-restrict-repos created
   k8sblockallingress.constraints.gatekeeper.sh/mitre-v2024-block-all-ingress created
   k8scronjoballowedrepos.constraints.gatekeeper.sh/mitre-v2024-cronjob-restrict-repos created
   k8sdisallowanonymous.constraints.gatekeeper.sh/mitre-v2024-no-anonymous created
   k8snoenvvarsecrets.constraints.gatekeeper.sh/mitre-v2024-no-secrets-as-env-vars created
   k8spspapparmor.constraints.gatekeeper.sh/mitre-v2024-apparmor created
   k8spspcapabilities.constraints.gatekeeper.sh/mitre-v2024-restrict-capabilities created
   k8spspforbiddensysctls.constraints.gatekeeper.sh/mitre-v2024-sysctls created
   k8spsphostfilesystem.constraints.gatekeeper.sh/mitre-v2024-restrict-hostpath-volumes created
   k8spsphostnamespace.constraints.gatekeeper.sh/mitre-v2024-host-namespaces-host-pid-ipc created
   k8spsphostnetworkingports.constraints.gatekeeper.sh/mitre-v2024-host-namespaces-hostnetwork created
   k8spsphostnetworkingports.constraints.gatekeeper.sh/mitre-v2024-host-ports created
   k8spspprivilegedcontainer.constraints.gatekeeper.sh/mitre-v2024-privileged-containers created
   k8spspprocmount.constraints.gatekeeper.sh/mitre-v2024-proc-mount-type created
   k8spspselinuxv2.constraints.gatekeeper.sh/mitre-v2024-selinux created
   k8spspseccomp.constraints.gatekeeper.sh/mitre-v2024-seccomp created
   k8spspwindowshostprocess.constraints.gatekeeper.sh/mitre-v2024-restrict-windows-hostprocess created
   k8srequirebinauthz.constraints.gatekeeper.sh/mitre-v2024-require-binauthz created
   k8srequirenamespacenetworkpolicies.constraints.gatekeeper.sh/mitre-v2024-require-namespace-networkpolicy created
   k8srestrictadmissioncontroller.constraints.gatekeeper.sh/mitre-v2024-restrict-admission-controller created
   k8srestrictautomountserviceaccounttokens.constraints.gatekeeper.sh/mitre-v2024-restrict-automountserviceaccounttoken created
   k8srestrictnamespaces.constraints.gatekeeper.sh/mitre-v2024-restrict-kubernetes-dashboard-namespace created
   k8srestrictrbacsubjects.constraints.gatekeeper.sh/mitre-v2024-restrict-rbac-subjects created
   k8srestrictrolebindings.constraints.gatekeeper.sh/mitre-v2024-restrict-cluster-admin-role created
   k8srestrictrolerules.constraints.gatekeeper.sh/mitre-v2024-restrict-pods-exec created
   k8srestrictrolerules.constraints.gatekeeper.sh/mitre-v2024-restrict-role-secrets created
   

3. Verify that policy constraints have been installed and check if violations exist across the cluster:

   kubectl get constraints -l policycontroller.gke.io/bundleName=mitre-v2024
   

   The output is similar to the following:

   NAME                                                                   ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8sallowedrepos.constraints.gatekeeper.sh/mitre-v2024-restrict-repos   dryrun               0
   
   NAME                                                                         ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8sblockallingress.constraints.gatekeeper.sh/mitre-v2024-block-all-ingress   dryrun               0
   
   NAME                                                                                  ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8scronjoballowedrepos.constraints.gatekeeper.sh/mitre-v2024-cronjob-restrict-repos   dryrun               0
   
   NAME                                                                      ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8sdisallowanonymous.constraints.gatekeeper.sh/mitre-v2024-no-anonymous   dryrun               0
   
   NAME                                                                              ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8snoenvvarsecrets.constraints.gatekeeper.sh/mitre-v2024-no-secrets-as-env-vars   dryrun               0
   
   NAME                                                            ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspapparmor.constraints.gatekeeper.sh/mitre-v2024-apparmor   dryrun               0
   
   NAME                                                                             ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspcapabilities.constraints.gatekeeper.sh/mitre-v2024-restrict-capabilities   dryrun               0
   
   NAME                                                                   ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspforbiddensysctls.constraints.gatekeeper.sh/mitre-v2024-sysctls   dryrun               0
   
   NAME                                                                                   ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spsphostfilesystem.constraints.gatekeeper.sh/mitre-v2024-restrict-hostpath-volumes   dryrun               0
   
   NAME                                                                                     ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spsphostnamespace.constraints.gatekeeper.sh/mitre-v2024-host-namespaces-host-pid-ipc   dryrun               0
   
   NAME                                                                                          ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spsphostnetworkingports.constraints.gatekeeper.sh/mitre-v2024-host-namespaces-hostnetwork   dryrun               0
   k8spsphostnetworkingports.constraints.gatekeeper.sh/mitre-v2024-host-ports                    dryrun               0
   
   NAME                                                                                    ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspprivilegedcontainer.constraints.gatekeeper.sh/mitre-v2024-privileged-containers   dryrun               0
   
   NAME                                                                    ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspprocmount.constraints.gatekeeper.sh/mitre-v2024-proc-mount-type   dryrun               0
   
   NAME                                                          ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspseccomp.constraints.gatekeeper.sh/mitre-v2024-seccomp   dryrun               0
   
   NAME                                                            ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspselinuxv2.constraints.gatekeeper.sh/mitre-v2024-selinux   dryrun               0
   
   NAME                                                                                          ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8spspwindowshostprocess.constraints.gatekeeper.sh/mitre-v2024-restrict-windows-hostprocess   dryrun               0
   
   NAME                                                                        ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8srequirebinauthz.constraints.gatekeeper.sh/mitre-v2024-require-binauthz   dryrun               0
   
   NAME                                                                                                       ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8srequirenamespacenetworkpolicies.constraints.gatekeeper.sh/mitre-v2024-require-namespace-networkpolicy   dryrun               0
   
   NAME                                                                                                 ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8srestrictadmissioncontroller.constraints.gatekeeper.sh/mitre-v2024-restrict-admission-controller   dryrun               0
   
   NAME                                                                                                                   ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8srestrictautomountserviceaccounttokens.constraints.gatekeeper.sh/mitre-v2024-restrict-automountserviceaccounttoken   dryrun               0
   
   NAME                                                                                                  ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8srestrictnamespaces.constraints.gatekeeper.sh/mitre-v2024-restrict-kubernetes-dashboard-namespace   dryrun               0
   
   NAME                                                                                   ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8srestrictrbacsubjects.constraints.gatekeeper.sh/mitre-v2024-restrict-rbac-subjects   dryrun               0
   
   NAME                                                                                        ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8srestrictrolebindings.constraints.gatekeeper.sh/mitre-v2024-restrict-cluster-admin-role   dryrun               0
   
   NAME                                                                               ENFORCEMENT-ACTION   TOTAL-VIOLATIONS
   k8srestrictrolerules.constraints.gatekeeper.sh/mitre-v2024-restrict-pods-exec      dryrun               0
   k8srestrictrolerules.constraints.gatekeeper.sh/mitre-v2024-restrict-role-secrets   dryrun               0
   

kpt

1. Install and setup kpt. kpt is used in these instructions to customize and deploy Kubernetes resources.

2. Download the MITRE policy bundle from GitHub using kpt:

   kpt pkg get https://github.com/GoogleCloudPlatform/gke-policy-library.git/anthos-bundles/mitre-v2024
   

3. Run the set-enforcement-action kpt function to set the policies' enforcement action to dryrun:

   kpt fn eval mitre-v2024 -i gcr.io/kpt-fn/set-enforcement-action:v0.1 \
     -- enforcementAction=dryrun
   

4. Initialize the working directory with kpt, which creates a resource to track changes:

   cd mitre-v2024
   kpt live init
   

5. Apply the policy constraints with kpt:

   kpt live apply
   

6. Verify that policy constraints have been installed and check if violations exist across the cluster:

   kpt live status --output table --poll-until current
   

   A status of CURRENT confirms successful installation of the constraints.

Config Sync

1. Install and setup kpt. kpt is used in these instructions to customize and deploy Kubernetes resources.

Operators using Config Sync to deploy policies to their clusters can use the following instructions:

1. Change into the sync directory for Config Sync:

   cd SYNC_ROOT_DIR
   

   Note: Kpt v1.0.0-beta.17 and later automatically create a resourcegroup.yaml file during live init which shouldn't be checked into your Config Sync repository. If not already present, add resourcegroup.yaml to your repo's .gitignore file.

   To create or append .gitignore with resourcegroup.yaml:

   echo resourcegroup.yaml >> .gitignore
   

2. Create a dedicated policies directory:

   mkdir -p policies
   

3. Download the MITRE policy bundle from GitHub using kpt:

   kpt pkg get https://github.com/GoogleCloudPlatform/gke-policy-library.git/anthos-bundles/mitre-v2024 policies/mitre-v2024
   

4. Run the set-enforcement-action kpt function to set the policies' enforcement action to dryrun:

   kpt fn eval policies/mitre-v2024 -i gcr.io/kpt-fn/set-enforcement-action:v0.1 -- enforcementAction=dryrun
   

5. (Optional) Preview the policy constraints to be created:

   kpt live init policies/mitre-v2024
   kpt live apply --dry-run policies/mitre-v2024
   

6. If your sync directory for Config Sync uses Kustomize, add policies/mitre-v2024 to your root kustomization.yaml. Otherwise remove the policies/mitre-v2024/kustomization.yaml file:

   rm SYNC_ROOT_DIR/policies/mitre-v2024/kustomization.yaml
   

7. Push changes to the Config Sync repository:

   git add SYNC_ROOT_DIR/policies/mitre-v2024
   git commit -m 'Adding MITRE policy audit enforcement'
   git push
   

8. Verify the status of the installation:

   watch gcloud beta container fleet config-management status --project PROJECT_ID
   

   A status of SYNCED confirms the installation of the policies.

View policy violations

Once the policy constraints are installed in audit mode, violations on the cluster can be viewed in the UI using the Policy Controller Dashboard.

You can also use kubectl to view violations on the cluster using the following command:

kubectl get constraint -l policycontroller.gke.io/bundleName=mitre-v2024 -o json | jq -cC '.items[]| [.metadata.name,.status.totalViolations]'

If violations are present, a listing of the violation messages per constraint can be viewed with:

kubectl get constraint -l policycontroller.gke.io/bundleName=mitre-v2024 -o json | jq -C '.items[]| select(.status.totalViolations>0)| [.metadata.name,.status.violations[]?]'

Change MITRE policy bundle enforcement action

Once you've reviewed policy violations on your cluster, you can consider changing the enforcement mode so the Admission Controller will either warn on or even deny block non-compliant resource from getting applied to the cluster.

Warning: The deny enforcement action should be used with care as it can potentially block required changes resulting in interruption to critical workloads or the cluster. It is strongly recommended that only the warn or dryrun enforcement actions are used on clusters with production workloads, when testing new constraints, or performing migrations such as upgrading platforms. For more information about enforcement actions, see Auditing using constraints.

kubectl

1. Use kubectl to set the policies' enforcement action to warn:

   kubectl get constraint -l policycontroller.gke.io/bundleName=mitre-v2024 -o name | xargs -I {} kubectl patch {} --type='json' -p='[{"op":"replace","path":"/spec/enforcementAction","value":"warn"}]'
   

2. Verify that policy constraints enforcement action have been updated:

   kubectl get constraint -l policycontroller.gke.io/bundleName=mitre-v2024
   

kpt

1. Run the set-enforcement-action kpt function to set the policies' enforcement action to warn:

   kpt fn eval -i gcr.io/kpt-fn/set-enforcement-action:v0.1 -- enforcementAction=warn
   

2. Apply the policy constraints:

   kpt live apply
   

Config Sync

Operators using Config Sync to deploy policies to their clusters can use the following instructions:

1. Change into the sync directory for Config Sync:

   cd SYNC_ROOT_DIR
   

2. Run the set-enforcement-action kpt function to set the policies' enforcement action to warn:

   kpt fn eval policies/mitre-v2024 -i gcr.io/kpt-fn/set-enforcement-action:v0.1 -- enforcementAction=warn
   

3. Push changes to the Config Sync repository:

   git add SYNC_ROOT_DIR/policies/mitre-v2024
   git commit -m 'Adding MITRE policy bundle warn enforcement'
   git push
   

4. Verify the status of the installation:

   gcloud alpha anthos config sync repo list --project PROJECT_ID
   

   Your repository showing up in the SYNCED column confirms the installation of the policies.

Test policy enforcement

Create a non-compliant resource on the cluster using the following command:

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
  namespace: default
  name: wp-non-compliant
  labels:
    app: wordpress
spec:
  containers:
    - image: wordpress
      name: wordpress
      ports:
      - containerPort: 80
        name: wordpress
EOF

The admission controller should produce a warning listing out the policy violations that this resource violates, as shown in the following example:

Warning: [mitre-v2024-restrict-repos] container <wordpress> has an invalid image repo <wordpress>, allowed repos are ["gcr.io/gke-release/", "gcr.io/anthos-baremetal-release/", "gcr.io/gke-on-prem-release/", "gcr.io/gke-multi-cloud-release/", "gcr.io/config-management-release/", "gcr.io/kubebuilder/", "gcr.io/gkeconnect/", "gke.gcr.io/"]
pod/wp-non-compliant created

Remove MITRE policy bundle

If needed, the MITRE policy bundle can be removed from the cluster.

kubectl

• Use kubectl to remove the policies:

  kubectl delete constraint -l policycontroller.gke.io/bundleName=mitre-v2024
  

kpt

• Remove the policies:

  kpt live destroy
  

Config Sync

Operators using Config Sync to deploy policies to their clusters can use the following instructions:

1. Push changes to the Config Sync repository:

   git rm -r SYNC_ROOT_DIR/policies/mitre-v2024
   git commit -m 'Removing MITRE policies'
   git push
   

2. Verify the status:

   gcloud alpha anthos config sync repo list --project PROJECT_ID
   

   Your repository showing up in the SYNCED column confirms the removal of the policies.