5.1.2 Minimize access to secrets

Information

The Kubernetes API stores secrets, which may be service account tokens for the Kubernetes API or credentials used by workloads in the cluster. Access to these secrets should be restricted to the smallest possible group of users to reduce the risk of privilege escalation.

Rationale:

Inappropriate access to secrets stored within the Kubernetes cluster can allow for an attacker to gain additional access to the Kubernetes cluster or external resources whose credentials are stored as secrets.

Impact:

Care should be taken not to remove access to secrets to system components which require this for their operation

NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.

Solution

Where possible, remove get, list and watch access to secret objects in the cluster.

Default Value:

By default in a OpenShift cluster the following list of principals have get privileges on secret objects

for i in $(oc get clusterroles -o jsonpath='{.items[*].metadata.name}'); do oc describe clusterrole ${i}; done

# The following default cluster roles have get privileges on secret objects

admin

cloud-credential-operator-role

cluster-admin

cluster-image-registry-operator

cluster-monitoring-operator

cluster-node-tuning-operator

edit

kube-state-metrics

machine-config-controller

marketplace-operator

openshift-ingress-operator

prometheus-operator

registry-admin

registry-editor

system:aggregate-to-edit

system:controller:expand-controller

system:controller:generic-garbage-collector

system:controller:namespace-controller

system:controller:operator-lifecycle-manager

system:controller:persistent-volume-binder

system:kube-controller-manager

system:master

system:node

system:openshift:controller:build-controller

system:openshift:controller:cluster-quota-reconciliation-controller

system:openshift:controller:ingress-to-route-controller

system:openshift:controller:service-ca

system:openshift:controller:service-serving-cert-controller

system:openshift:controller:serviceaccount-pull-secrets-controller

system:openshift:controller:template-service-broker

See Also

https://workbench.cisecurity.org/benchmarks/16094

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-4, CSCv7|13.4

Plugin: OpenShift

Control ID: 209748ce50139e6519c8aaed00436b7fcc3ddabec361ae1546563b287ef42527