Amazon EKS
TMA-EKS-4.1.5
Ensure that default service accounts are not actively used.
Description
Default service accounts in EKS should not be used as the active identity for ordinary application or automation workloads. If a Pod does not specify a service account, Kubernetes automatically assigns the namespace default service account, and that account can authenticate to the Kubernetes API through its mounted token. Requires kubectl with cluster-wide read access (KUBECONFIG); system namespaces are excluded and listed resources must be remediated or documented as exceptions. Fails when a default service account does not set automountServiceAccountToken: false or is bound to a Role/ClusterRole.
How it is checked
Audit method: Shell command
sa=$(kubectl get serviceaccounts -A -o go-template='{{range .items}}{{if eq .metadata.name "default"}}{{.metadata.namespace}} {{.automountServiceAccountToken}}{{"\n"}}{{end}}{{end}}') || exit 1
rb=$(kubectl get rolebindings,clusterrolebindings -A -o go-template='{{range .items}}{{$b:=.metadata.name}}{{$bn:=.metadata.namespace}}{{range .subjects}}{{if eq .kind "ServiceAccount"}}{{if eq .name "default"}}{{if .namespace}}{{.namespace}}{{else}}{{$bn}}{{end}} {{$b}}{{"\n"}}{{end}}{{end}}{{end}}{{end}}') || exit 1
bad=$(printf '%s\n' "$sa" | awk -v ex='^(kube-system|kube-public|kube-node-lease)$' 'NF && $1 !~ ex && $2!="false" {print "automount: " $1}')
bad2=$(printf '%s\n' "$rb" | awk -v ex='^(kube-system|kube-public|kube-node-lease)$' 'NF && $1 !~ ex {print "binding: " $0}')
if [ -z "$bad$bad2" ]; then echo compliant; else printf '%s\n%s\n' "$bad" "$bad2" | grep . | head -n 25; fi- Expected output
compliant
How it is fixed
Fix method: Guidance or infrastructure patch
Create dedicated service accounts for workloads that need Kubernetes API access, IRSA, or EKS Pod Identity, and update those workloads to explicitly set serviceAccountNam rather than relying on the namespace default service account. For workloads that do not need Kubernetes API access, disable service account token auto-mounting and avoid using the default service account as the active workload identity. Also review the default service account in each namespace and ensure it is not bound to unnecessary RBAC permissions.
Properties
- Operating systems
- Any
- Tags
- ekspoliciesrbac
- Reference
- CIS Amazon Elastic Kubernetes Service (EKS) Benchmark v2.0.0 - 4.1.5 Ensure that default service accounts are not actively used.
Check this host
Run this on a machine you are allowed to audit. The scan is read-only.
tmaegis scan --target eks