# At least one Conditional Access policy is configured to block legacy authentication for Exchange ActiveSync

At least one Conditional Access policy is configured to block legacy authentication for Exchange ActiveSync: Legacy authentication is an unsecure method to…

Source: https://maester.dev/docs/tests/MT.1010

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<div class="test-byline"><div class="test-byline-avatars"><a class="test-byline-avatar test-byline-avatar--author" href="/contributors/f-bader" title="Fabian Bader · Original author"><img src="https://github.com/f-bader.png" alt="Fabian Bader" 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/f-bader">Fabian Bader</a></span><a class="test-byline-link" href="/contributors">All contributors →</a></div></div>

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

```powershell title="Run this check"
Invoke-Maester -TestId MT.1010
```

## Overview

Legacy authentication is an unsecure method to authenticate. This function checks if the tenant has at least one
Conditional Access policy that blocks legacy authentication.

Learn more:
https://learn.microsoft.com/entra/identity/conditional-access/howto-conditional-access-policy-block-legacy

#### Remediation action

Review the configuration described above.

## Details

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

| Field | Value |
| --- | --- |
| Test ID | MT.1010 |
| Severity | High |
| Suite | Maester |
| Product | Entra ID |
| Related products | Exchange Online |
| Feature | Conditional Access |
| Area | Authentication |
| Resource type | Tenant |
| User impact | Medium |
| Implementation cost | Medium |
| MITRE ATT&CK | T1078.004 Cloud Accounts, T1110 Brute Force |
| Supports controls | nist-800-53-r5:CM-7 |
| PowerShell test | [Test-MtCaBlockLegacyExchangeActiveSyncAuthentication](https://github.com/maester365/maester/blob/main/tests/maester/entra/Test.MT.1010.ps1) |
| Services | Graph |
| Compatible licenses | AAD_PREMIUM |

</details>

## Source

- Test: [`tests/maester/entra/Test.MT.1010.ps1`](https://github.com/maester365/maester/blob/main/tests/maester/entra/Test.MT.1010.ps1)
- Documentation: [`tests/maester/entra/Test.MT.1010.md`](https://github.com/maester365/maester/blob/main/tests/maester/entra/Test.MT.1010.md)