# User SPN service class count should be investigated

Understanding the service classes of SPNs on user accounts helps security teams:

Source: https://maester.dev/docs/tests/AD-SPN-07

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<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 · Service principal names · <a href="/docs/tests">All checks</a></p>

```powershell title="Run this check"
Invoke-Maester -TestId AD-SPN-07
```

## Overview

Understanding the service classes of SPNs on user accounts helps security teams:

- **Identify service types**: Know what services are running under user credentials
- **Assess risk**: Some service classes (like MSSQLSvc) are higher-value targets
- **Detect anomalies**: Unexpected service classes may indicate unauthorized services
- **Plan migrations**: Identify candidates for migration to gMSAs

User accounts with database or application service SPNs are particularly sensitive.

#### Control Type

**Operational**

#### Security Recommendation

Review service classes on user accounts:
- Database services (MSSQLSvc, oracle, postgres) should use gMSAs
- Web services (HTTP, HTTPS) should run under service accounts or gMSAs
- Legacy service classes may indicate outdated applications
- Document all user accounts with SPNs and their purposes

#### How the Test Works

This test retrieves all user objects with SPNs, extracts the service class from each SPN, and counts the distinct service classes in use.

#### Related Tests

- `Test-MtAdUserSpnServiceClassUsage` - Detailed breakdown of service class usage
- `Test-MtAdUserSpnTotalCount` - Total count of user SPNs
- `Test-MtAdComputerSpnServiceClassCount` - Computer account service classes

## Details

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

| Field | Value |
| --- | --- |
| Test ID | AD-SPN-07 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | Service principal names |
| Area | Authentication |
| Resource type | User |
| MITRE ATT&CK | T1558.003 Kerberoasting |
| PowerShell test | [Test-MtAdUserSpnServiceClassCount](https://github.com/maester365/maester/blob/main/tests/ad/spn/Test.AD-SPN-07.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Ldap:user:ReadProperty |

</details>

## Source

- Test: [`tests/ad/spn/Test.AD-SPN-07.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/spn/Test.AD-SPN-07.ps1)
- Documentation: [`tests/ad/spn/Test.AD-SPN-07.md`](https://github.com/maester365/maester/blob/main/tests/ad/spn/Test.AD-SPN-07.md)