Cis K8s V1110 4.2.15

---
name: cis-k8s-v1110-4.2.15
description: "Ensure that the --IPAddressDeny is set to any (Manual)"
category: cis-k8s
version: "1.11.0"
author: cyberstrike-official
tags: [cis, kubernetes, worker-node, kubelet, ip-address-deny, network-security, ip-filtering]
cis_id: "4.2.15"
cis_benchmark: "CIS Kubernetes Benchmark v1.11.0"
tech_stack: [kubernetes]
cwe_ids: []
chains_with: []
prerequisites: []
severity_boost: {}
---

# 4.2.15 Ensure that the --IPAddressDeny is set to any (Manual)

## Profile Applicability

- Level 2 - Worker Node

## Description

Ensuring that `--IPAddressDeny` is set to "Any" will facilitate allowlisting of only IP addresses that are explicitly set with the `--IPAddressAllow` parameter which will block unspecified IP addresses from communicating with the kubelet component.

## Rationale

By default, Kubernetes allows any IP address to communicate with the kubelet component IP restrictions and IP whitelisting are security best practices and reduce the attack surface of the kubelet.

## Impact

Configuring the setting `IPAddressDeny=any` will deny service to any IP address not specified in the complimentary setting `IPAddressDeny=any` configuration parameter. Applying `IPAddressDeny=any` alone will completely disable communication with the component.

## Audit

Review the Kubelet's start-up parameters for the value of `--IPAddressDeny`, and check the Kubelet configuration file for `IPAddressDeny=any`.
If this entry is present it should be accompanied by `IPAddressAllow={{ kubelet_secure_addresses }}` to allow the control plane to communicate with the component.

## Remediation

```
IPAddressDeny=any
IPAddressAllow={{ kubelet_secure_addresses }}
```

\*Note
kubelet_secure_addresses: "localhost link-local {{ kube_pods_subnets | regex_replace(',', ' ') }} {{ kube_node_addresses }} {{ loadbalancer_apiserver.address | default("") }}"

## Default Value

By default IPAddressDeny is not enabled.

## References

1. [https://github.com/kubernetes-sigs/kubespray/pull/9194/files](https://github.com/kubernetes-sigs/kubespray/pull/9194/files)
2. [https://kubernetes.io/docs/concepts/services-networking/network-policies/](https://kubernetes.io/docs/concepts/services-networking/network-policies/)

## CIS Controls

| Controls Version | Control                                           | IG 1 | IG 2 | IG 3 |
| ---------------- | ------------------------------------------------- | ---- | ---- | ---- |
| v8               | 2.5 Allowlist Authorized Software                 |      | x    | x    |
| v8               | 2.7 Allowlist Authorized Scripts                  |      |      | x    |
| v7               | 2.7 Utilize Application Whitelisting              |      |      | x    |
| v7               | 2.9 Implement Application Whitelisting of Scripts |      |      | x    |