Mastering CIS Remediation at Scale: Inside My ESXi Hardening Script

Includes Downloadable Script

Why I Built This

CIS alignment is easy to talk about and hard to operationalize.

At any real scale, the problem isn’t “what setting should this be?” — the problem is safely enforcing it across hundreds (or thousands) of hosts, across multiple vCenters, without breaking operations, without losing audit evidence, and with a clean way to unwind changes if something unexpected surfaces.

That’s what Master_CIS_Remediation v5.8.6 is designed to do:

enforce CIS-aligned ESXi host configuration
log every action
provide a dry-run mode
and support backout using a captured backup CSV

This is not a one-off “run it once and forget it” script. It’s meant to be a repeatable compliance tool.

Design Goals

These were my non-negotiables when building this:

PowerShell 5.1 compatible
Operator-friendly UX (same flow and feel as my Audit script)
Idempotent checks (if the host is already compliant, do nothing)
Evidence-first logging (every pass/fail/change is recorded)
Backout-capable by design (restore from captured pre-change values)

Script Modes

The script supports three execution modes:

AuditOnly (dry run)

Runs all checks, makes no changes, and skips change logging.

Remediation (default)

Performs the checks and applies changes when non-compliance is found.

Backout

Restores settings from a backup CSV produced during a remediation run.

Credential Handling (Multi-vCenter Friendly)

This script supports a simple, repeatable credential workflow using exported credential files. The credential file is created per vCenter FQDN and stored here:

%USERPROFILE%\Documents\vcentercreds\<vcenter>.xml

This keeps the operator experience smooth when you’re frequently adding new vCenters.

Logging (Proof Matters)

All output CSVs land in:

C:\Temp

The script writes distinct outputs for clarity:

Remediation results: Master_CIS_Remediation_<timestamp>.csv
Backups for backout: Master_CIS_Backup_<timestamp>.csv
Backout results: Master_CIS_Backout_<timestamp>.csv

This separation is intentional:

remediation = “what I changed”
backup = “what it was before”
backout = “what I restored”

What It Enforces (v5.8.6)

The v5.8.6 menu-driven checks include:

Mem.ShareForceSalting
ESXi Shell (TSM)
SSH (TSM-SSH)
NTP & ntpd
SNMP
Persistent logging
Remote logging
SSH Connection Banner
SLP service (slpd)
SSH service policy Manual
Account lockout failures
DVFilter Bind IP
Password Complexity
Managed Object Browser (MOB)
Hyperthreading warning
iSCSI Mutual CHAP (may require reboot)

How to Run It

Dry run (recommended first)

.\Master_CIS_Remediation_v5.8.6.ps1 -AuditOnly

Remediation run

.\Master_CIS_Remediation_v5.8.6.ps1

Backout run

.\Master_CIS_Remediation_v5.8.6.ps1 -Backout

Or specify the CSV directly:

.\Master_CIS_Remediation_v5.8.6.ps1 -Backout -BackoutCsv "C:\Temp\Master_CIS_Backup_YYYYMMDD_HHMMSS.csv"

Operational Notes I Care About

Run AuditOnly first to validate scope and reduce surprises.
Keep evidence CSVs like change tickets.
CIS controls can have real operational impact—roll out carefully.
Backout is not optional; it’s how you build trust in automation.

What’s Next

This script is one piece of a broader compliance workflow. Future directions include enhanced reporting, tighter pre-flight checks, and deeper control-to-risk mapping. If you’re running ESXi at scale and trying to keep standards consistent without living in manual remediation forever, this approach is worth building into your toolbox.

Download the Script

A public, sanitized version of this script is available for download below.

👉 Download Master_CIS_Remediation_v5.8.6_SANITIZED.ps1

⚠️ This script is provided as-is for educational purposes.
Always review and test in a lab environment before running in production.