# Legacy authentication SHALL be blocked

Rationale: The security risk of allowing legacy authentication protocols is they do not support MFA.

Source: https://maester.dev/docs/tests/CISA.MS.AAD.1.1

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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><a class="test-byline-avatar" href="/contributors/merill" title="Merill Fernando · Co-contributor"><img src="https://github.com/merill.png" alt="Merill Fernando" width="28" height="28" loading="lazy" decoding="async" /></a><a class="test-byline-avatar" href="/contributors/andremieth" title="André Mieth · Co-contributor"><img src="https://github.com/andremieth.png" alt="André Mieth" 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> with 2 co-contributors</span><a class="test-byline-link" href="/contributors">All contributors →</a></div></div>

<p class="test-part">Part of <a href="/docs/tests/cisa">CISA</a> · Entra ID · Conditional Access · <a href="/docs/tests">All checks</a></p>

```powershell title="Run this check"
Invoke-Maester -TestId CISA.MS.AAD.1.1
```

## Overview

Legacy authentication SHALL be blocked.

Rationale: The security risk of allowing legacy authentication protocols is they do not support MFA. Blocking legacy protocols reduces the impact of user credential theft.

#### Remediation action:

Follow the guide below to create a Conditional Access policy that blocks legacy authentication.

- [Block legacy authentication - Microsoft Learn](https://learn.microsoft.com/entra/identity/conditional-access/howto-conditional-access-policy-block-legacy#create-a-conditional-access-policy)

#### Related links

- [CISA Legacy Authentication - MS.AAD.1.1v1](https://github.com/cisagov/ScubaGear/blob/main/PowerShell/ScubaGear/baselines/aad.md#1-legacy-authentication)
- [CISA ScubaGear Rego Reference](https://github.com/cisagov/ScubaGear/blob/main/PowerShell/ScubaGear/Rego/AADConfig.rego#L47)

## Details

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

| Field | Value |
| --- | --- |
| Test ID | CISA.MS.AAD.1.1 |
| Severity | High |
| Suite | CISA |
| Product | Entra ID |
| Feature | Conditional Access |
| Area | Authentication |
| Resource type | Tenant |
| User impact | Medium |
| Implementation cost | Medium |
| MITRE ATT&CK | T1110 Brute Force, T1078.004 Cloud Accounts |
| Supports benchmark | CISA SCuBA Secure Configuration Baselines for Microsoft 365 (version ScubaGear main, 2026-10-11), requirement MS.AAD.1.1 |
| Criticality | SHALL |
| Upstream requirement | MS.AAD.1.1v1 |
| Supports controls | cisa-scuba:MS.AAD.1.1, nist-800-53-r5:CM-7 |
| PowerShell test | [Test-MtCisaBlockLegacyAuth](https://github.com/maester365/maester/blob/main/tests/cisa/entra/Test.CISA.MS.AAD.1.1.ps1) |
| Services | Graph |
| Compatible licenses | AAD_PREMIUM |

</details>

## Source

- Test: [`tests/cisa/entra/Test.CISA.MS.AAD.1.1.ps1`](https://github.com/maester365/maester/blob/main/tests/cisa/entra/Test.CISA.MS.AAD.1.1.ps1)
- Documentation: [`tests/cisa/entra/Test.CISA.MS.AAD.1.1.md`](https://github.com/maester365/maester/blob/main/tests/cisa/entra/Test.CISA.MS.AAD.1.1.md)