The default namespace should not be used

LowLevel 2Automatedaks

Description

Avoid placing application workloads in the default namespace, and instead deploy them into dedicated namespaces that reflect the intended team, application, or environment boundary. In AKS, namespaces are the built-in way to logically divide cluster resources and scope access, while the default namespace exists mainly so a cluster can be used immediately without first creating a new namespace. Requires kubectl read access; fails when the default namespace holds objects other than the kubernetes Service, kube-root-ca.crt ConfigMap and default ServiceAccount.

How it is checked

Audit method: Shell command

shell

out=$(kubectl get pods,services,configmaps,secrets,serviceaccounts,deployments,statefulsets,daemonsets,jobs,cronjobs,ingresses,roles,rolebindings -n default -o name) || exit 1
bad=$(printf '%s\n' "$out" | grep -v '^$' | sed 's#^\([a-z]*\)\.[^/]*/#\1/#' | grep -Evx 'service/kubernetes|configmap/kube-root-ca\.crt|serviceaccount/default')
if [ -z "$bad" ]; then echo compliant; else printf '%s\n' "$bad" | head -n 25; fi

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Create purpose-specific namespaces for teams, applications, and environments, then require all new resources to be deployed into those namespaces instead of default. In AKS, namespaces are the logical boundary for workload administration, so remediation should include migrating existing resources into managed namespaces, applying namespace-scoped RBAC and other controls, and reserving cluster-wide access for true platform administrators only.

Properties

Operating systems: Any
Tags: akspolicies
Reference: CIS Azure Kubernetes Service (AKS) Benchmark v2.0.0 - 4.6.3 The default namespace should not be used

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target aks --level 2