Cis Oke V180 4.1.6

4.1.6 Ensure that Service Account Tokens are only mounted where necessary (Automated)

Profile Applicability

• Level 1

Description

Service accounts tokens should not be mounted in pods except where the workload running in the pod explicitly needs to communicate with the API server.

Rationale

Mounting service account tokens inside pods can provide an avenue for privilege escalation attacks where an attacker is able to compromise a single pod in the cluster.

Avoiding mounting these tokens removes this attack avenue.

Impact

Pods mounted without service account tokens will not be able to communicate with the API server, except where the resource is available to unauthenticated principals.

Audit

Review pod and service account objects in the cluster and ensure that the option below is set, unless the resource explicitly requires this access.

automountServiceAccountToken: false

echo "=== ServiceAccounts with automountServiceAccountToken=false ==="
printf "%-25s %-40s\n" "NAMESPACE" "SERVICEACCOUNT"
echo "------------------------- ----------------------------------------"
kubectl get sa -A -o jsonpath='{range .items[?(@.automountServiceAccountToken==false)]}{.metadata.namespace}{"\t"}{.metadata.name}{"\n"}{end}' \
| sort | awk -F'\t' '{printf "%-25s %-40s\n", $1, $2}'

echo ""
echo "=== Pods with automountServiceAccountToken=false ==="
printf "%-25s %-40s\n" "NAMESPACE" "POD"
echo "------------------------- ----------------------------------------"
kubectl get pods -A -o jsonpath='{range .items[?(@.spec.automountServiceAccountToken==false)]}{.metadata.namespace}{"\t"}{.metadata.name}{"\n"}{end}' \
| sort | awk -F'\t' '{printf "%-25s %-40s\n", $1, $2}'

Note:

• If a section is empty, no objects explicitly set automountServiceAccountToken: false -- meaning they still auto-mount tokens by default, and may need remediation.

Remediation

Modify the definition of pods and service accounts which do not need to mount service account tokens to disable it.

Default Value

By default, all pods get a service account token mounted in them.

References

1. https://kubernetes.io/docs/tasks/configure-pod-container/configure-service-account/

CIS Controls

MITRE ATT&CK Mappings