# User SID History count should be retrievable

SIDHistory is commonly used during migrations so users can retain access to resources secured with legacy SIDs.

Source: https://maester.dev/docs/tests/AD-USER-13

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

```powershell title="Run this check"
Invoke-Maester -TestId AD-USER-13
```

## Overview

`SIDHistory` is commonly used during migrations so users can retain access to resources secured with legacy SIDs. Long-term SID history can create unnecessary complexity and unintended access paths.

- **Migration artifact detection**: Identifies users that may still carry legacy identities
- **Trust boundary review**: Helps spot cross-domain access dependencies
- **Permission cleanup**: Supports least-privilege remediation after migrations

#### Control Type

**Detective**

#### Security Recommendation

- Review users with `SIDHistory` to confirm ongoing business need
- Remove unnecessary SID history entries after resource migration is complete
- Pay special attention to SIDs originating from external or less-trusted domains

#### How the Test Works

This test counts user objects where the `SIDHistory` attribute contains one or more values.

#### Related Tests

- `Test-MtAdUserNonStandardPrimaryGroupCount` - Finds other migration or provisioning anomalies
- `Test-MtAdUserAdminCountCount` - Helps prioritize review of privileged accounts

#### Related links

- [Microsoft Defender for Identity: Unsecure SID History attributes](https://learn.microsoft.com/defender-for-identity/security-posture-assessments/accounts#unsecure-sid-history-attributes)
- [ANSSI Active Directory checkpoints: Accounts or groups with SID history set](https://www.cert.ssi.gouv.fr/uploads/ad_checklist.html#vuln_sidhistory_present)

## Details

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

| Field | Value |
| --- | --- |
| Test ID | AD-USER-13 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | Users |
| Area | Identity lifecycle and hygiene |
| Resource type | User |
| MITRE ATT&CK | T1134.005 SID-History Injection |
| PowerShell test | [Test-MtAdUserSidHistoryCount](https://github.com/maester365/maester/blob/main/tests/ad/user/Test.AD-USER-13.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Ldap:user:ReadProperty |

</details>

## Source

- Test: [`tests/ad/user/Test.AD-USER-13.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/user/Test.AD-USER-13.ps1)
- Documentation: [`tests/ad/user/Test.AD-USER-13.md`](https://github.com/maester365/maester/blob/main/tests/ad/user/Test.AD-USER-13.md)