# Known service account details should be investigated

Service accounts often run business-critical workloads and commonly receive exceptions such as long-lived credentials, SPNs, or privileged access.

Source: https://maester.dev/docs/tests/AD-USER-21

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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 · Users · <a href="/docs/tests">All checks</a></p>

```powershell title="Run this check"
Invoke-Maester -TestId AD-USER-21
```

## Overview

Service accounts often run business-critical workloads and commonly receive exceptions such as long-lived credentials, SPNs, or privileged access. Naming-pattern reviews help defenders quickly identify accounts that deserve deeper validation.

- **Exposure reduction**: Find accounts likely used by services before attackers do.
- **Privilege review**: Verify service accounts are not over-privileged.
- **Credential hygiene**: Check for non-expiring passwords and stale patterns.
- **Inventory accuracy**: Confirm naming standards are applied consistently.

#### Control Type

**Operational**

#### Security Recommendation

- Maintain a defined naming standard for service accounts.
- Review matched accounts for owner, purpose, and required privileges.
- Prefer gMSAs where possible instead of traditional user-based service accounts.
- Investigate service-like names that lack documentation.

#### How the Test Works

This test reviews AD user objects and flags accounts whose `SamAccountName` or `Name` matches common service-account conventions such as `svc-`, `service-`, `app-`, `sql-`, or `admin-svc`.

#### Related Tests

- `Test-MtAdUserDelegationConfiguredCount`
- `Test-MtAdUserDelegationDetails`

## Details

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

| Field | Value |
| --- | --- |
| Test ID | AD-USER-21 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | Users |
| Area | Applications and workload identities |
| Resource type | User |
| MITRE ATT&CK | None |
| PowerShell test | [Test-MtAdUserKnownServiceAccountDetails](https://github.com/maester365/maester/blob/main/tests/ad/user/Test.AD-USER-21.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Ldap:user:ReadProperty |

</details>

## Source

- Test: [`tests/ad/user/Test.AD-USER-21.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/user/Test.AD-USER-21.ps1)
- Documentation: [`tests/ad/user/Test.AD-USER-21.md`](https://github.com/maester365/maester/blob/main/tests/ad/user/Test.AD-USER-21.md)