# Computer operating system count should be investigated

Security Implications: - Legacy Systems: Older operating systems may no longer receive security updates - Inconsistent Patching: Different OS versions may…

Source: https://maester.dev/docs/tests/AD-DCOMP-04

<!-- This file is generated by website/scripts/generate-test-docs.mjs. Do not edit manually. -->

<div class="test-byline"><div class="test-byline-avatars"><a class="test-byline-avatar test-byline-avatar--author" href="/contributors/soulemike" title="Michael Soule · Original author"><img src="https://github.com/soulemike.png" alt="Michael Soule" width="28" height="28" loading="lazy" decoding="async" /></a></div><div class="test-byline-meta"><span class="test-byline-text">Contributed by <a href="/contributors/soulemike">Michael Soule</a></span><a class="test-byline-link" href="/contributors">All contributors →</a></div></div>

<p class="test-part">Part of <a href="/docs/tests/ad">Active Directory</a> · Active Directory · Computers · <a href="/docs/tests">All checks</a></p>

```powershell title="Run this check"
Invoke-Maester -TestId AD-DCOMP-04
```

## Overview

- Understanding the distribution of operating systems in your Active Directory environment is crucial for security management. High OS diversity can indicate:

**Security Implications:**
- **Legacy Systems**: Older operating systems may no longer receive security updates
- **Inconsistent Patching**: Different OS versions may have varying patch levels
- **Unsupported Platforms**: End-of-life operating systems pose significant security risks
- **Compliance Issues**: Regulatory requirements may mandate specific OS versions

**Common Scenarios:**
- Windows Server 2008/2012 reaching end-of-life
- Mixed Windows and Linux environments
- Workstations running outdated client OS versions

#### Control Type

**Operational**

#### Security Recommendation

1. **Standardize Operating Systems**:
   - Minimize OS diversity where possible
   - Establish standard builds for servers and workstations
   - Maintain supported OS versions only

2. **Identify End-of-Life Systems**:
   - Create inventory of systems nearing end-of-life
   - Plan upgrade paths for legacy systems
   - Isolate unsupported systems if upgrades are delayed

3. **Patch Management**:
   - Ensure all systems receive regular security updates
   - Prioritize critical and high-severity patches
   - Test patches on representative OS versions

#### How the Test Works

This test analyzes computer objects in Active Directory and:
- Counts distinct operating systems
- Shows distribution percentages
- Identifies computers without OS data

#### Related Tests

- `Test-MtAdComputerOperatingSystemDetails` - Detailed OS and service pack information
- `Test-MtAdComputerStaleEnabledCount` - Identifies stale computer accounts
- `Test-MtAdDcOperatingSystemDetails` - Domain Controller OS distribution

## Details

<details>
<summary>Every attribute of this check</summary>

| Field | Value |
| --- | --- |
| Test ID | AD-DCOMP-04 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | Computers |
| Area | Devices and endpoints |
| Resource type | Computer |
| MITRE ATT&CK | None |
| Supports controls | nist-800-53-r5:CM-8 |
| PowerShell test | [Test-MtAdComputerOperatingSystemCount](https://github.com/maester365/maester/blob/main/tests/ad/security/Test.AD-DCOMP-04.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Ldap:computer:ReadProperty |

</details>

## Source

- Test: [`tests/ad/security/Test.AD-DCOMP-04.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/security/Test.AD-DCOMP-04.ps1)
- Documentation: [`tests/ad/security/Test.AD-DCOMP-04.md`](https://github.com/maester365/maester/blob/main/tests/ad/security/Test.AD-DCOMP-04.md)