Controller Manager Pod Specification File Ownership Should

More Info:

Verifies that the kube-controller-manager pod manifest file is owned by root:root so only privileged users can modify it.

Risk Level

Medium

Address

Security

Compliance Standards

• CIS Kubernetes

Triage and Remediation

Remediation

Remediation

Manual Steps

1. On every control plane node, check the current ownership of the manifest file:

   stat -c %U:%G /etc/kubernetes/manifests/kube-controller-manager.yaml

2. If the owner or group is not root:root, change the ownership on that control plane node:

   sudo chown root:root /etc/kubernetes/manifests/kube-controller-manager.yaml

3. (Optional) Confirm file still exists and note that editing a static pod manifest under /etc/kubernetes/manifests will trigger an automatic restart of the kube-controller-manager pod by the kubelet; no manual restart is needed.

4. Verify the fix on that control plane node:

   stat -c %U:%G /etc/kubernetes/manifests/kube-controller-manager.yaml

   The output must be:

   root:root

Using kubectl

kubectl cannot modify file ownership on control plane nodes, so it cannot be used to fix this finding on /etc/kubernetes/manifests/kube-controller-manager.yaml. To remediate, you must change ownership directly on every control plane node’s filesystem; see the Manual Steps section for exact commands.

Automation

#!/usr/bin/env bash
#
# Fix ownership of kube-controller-manager pod manifest to root:root
# Scope: run on every control plane node
# Idempotent: safe to run multiple times

set -euo pipefail

MANIFEST_PATH="/etc/kubernetes/manifests/kube-controller-manager.yaml"

echo "==> Checking for kube-controller-manager manifest at ${MANIFEST_PATH}"

if [ ! -e "${MANIFEST_PATH}" ]; then
  echo "Manifest file not found at ${MANIFEST_PATH}. Nothing to do on this node."
  exit 0
fi

current_owner_group="$(stat -c '%U:%G' "${MANIFEST_PATH}")"

echo "Current ownership: ${current_owner_group}"

if [ "${current_owner_group}" = "root:root" ]; then
  echo "Ownership already set to root:root. No change needed."
else
  echo "Setting ownership to root:root ..."
  chown root:root "${MANIFEST_PATH}"
fi

# Verification
echo "==> Verifying ownership after changes"
verified_owner_group="$(stat -c '%U:%G' "${MANIFEST_PATH}")"
echo "Verified ownership: ${verified_owner_group}"

if [ "${verified_owner_group}" != "root:root" ]; then
  echo "ERROR: Failed to set ownership to root:root on ${MANIFEST_PATH}" >&2
  exit 1
fi

echo "Ownership successfully set to root:root on ${MANIFEST_PATH}"

Usage:

• Run this script on every control plane node (e.g., via SSH or your configuration management/automation system).