SV-242430r1043178: Kubernetes etcd must have a certificate for communication. | Kubernetes STIG SCAP Benchmark

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Assessment Title

Rule Text

Kubernetes etcd must have a certificate for communication.

Description

Discussion Text

Kubernetes stores configuration and state information in a distributed key-value store called etcd. Anyone who can write to etcd can effectively control the Kubernetes cluster. Even just reading the contents of etcd could easily provide helpful hints to a would-be attacker. Using authenticity protection, the communication can be protected against man-in-the-middle attacks/session hijacking and the insertion of false information into sessions. The communication session is protected by utilizing transport encryption protocols, such as TLS. TLS provides the Kubernetes API Server and etcd with a means to be able to authenticate sessions and encrypt traffic. To enable encrypted communication for etcd, the parameter "--etcd-certfile" must be set. This parameter gives the location of the SSL certification file used to secure etcd communication.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-001184

References

DPMS Target Kubernetes DISA DPMS Target Kubernetes 5376

Checks

DISA STIG (Manual Reference)

Change to the /etc/kubernetes/manifests directory on the Kubernetes Control Plane. Run the command:
grep -i etcd-certfile * 

If the setting "--etcd-certfile" is not set in the Kubernetes API Server manifest file, this is a finding.

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.stig.kubernetes:def:242430
# Kubernetes etcd must have a certificate for communication.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# textfilecontent54_object (textfilecontent54_test)
test_1() {
  grep -Pq '^[ -]*etcd-certfile=\S+' '/etc/kubernetes/manifests/kube-apiserver.yaml' &>/dev/null
}

if test_1; then
  echo "PASS"
else
  echo "FAIL"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# OVAL Definition: oval:mil.disa.stig.kubernetes:def:242430


if [ ! -f "/etc/kubernetes/manifests/kube-apiserver.yaml" ]; then echo "PASS"; exit 0; fi
if grep -q "^[ -]*etcd-certfile=\\S+" /etc/kubernetes/manifests/kube-apiserver.yaml && grep -c "^[ -]*etcd-certfile=\\S+" /etc/kubernetes/manifests/kube-apiserver.yaml -ge 1 ]; then echo "PASS"; exit 0; else echo "FAIL"; exit 1; fi

Remediation

Edit the Kubernetes API Server manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Control Plane. 

Set the value of "--etcd-certfile" to the certificate to be used for communication with etcd.