SV-242384r1137638: The Kubernetes Scheduler must have secure binding. | Kubernetes STIG SCAP Benchmark

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Assessment Title

Rule Text

The Kubernetes Scheduler must have secure binding.

Description

Discussion Text

Limiting the number of attack vectors and implementing authentication and encryption on the endpoints available to external sources is paramount when securing the overall Kubernetes cluster. The Scheduler API service exposes port 10251/TCP by default for health and metrics information use. This port does not encrypt or authenticate connections. If this port is exposed externally, an attacker can use this port to attack the entire Kubernetes cluster. By setting the bind address to localhost (i.e., 127.0.0.1), only those internal services that require health and metrics information can access the Scheduler API.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000213

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 bind-address * 

If the setting "bind-address" is not set to "127.0.0.1" or is not found in the Kubernetes Scheduler 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:242384
# The Kubernetes Scheduler must have secure binding.
# 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() {
  (sed -En 's/^(?i)[ -]*bind-address=([\d\.]+)/\1/p' '/etc/kubernetes/manifests/kube-scheduler.yaml') | grep -qxF '127.0.0.1'
}

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:242384

if [ ! -f "/etc/kubernetes/manifests/kube-scheduler.yaml" ]; then
  echo "PASS"
  exit 0
fi

content=$(cat "/etc/kubernetes/manifests/kube-scheduler.yaml")
if grep -q "^[[:space:]]*bind-address=127.0.0.1$" <<< "$content"; then
  echo "PASS"
  exit 0
else
  echo "FAIL"
  exit 1
fi

Remediation

Edit the Kubernetes Scheduler manifest file in the /etc/kubernetes/manifests directory on the Kubernetes Control Plane. Set the argument "--bind-address" to "127.0.0.1".