CISA.MS.EXO.15.1 - URL comparison with a block-list SHOULD be enabled.

Overview

URL comparison with a block-list SHOULD be enabled.

Rationale: Users may be directed to malicious websites via links in email. Blocking access to known, malicious URLs can prevent users from accessing known malicious websites.

Remediation action:

1. Sign in to Microsoft 365 Defender.
2. In the left-hand menu, go to Email & Collaboration > Policies & Rules.
3. Select Threat Policies.
4. From the Templated policies section, select Preset Security Policies.
5. Under either Standard protection or Strict protection, select Manage protection settings.
6. Select Next until you reach the Apply Defender for Office 365 protection page.
7. On the Apply Defender for Office 365 protection page, select All recipients.
8. (Optional) Under Exclude these recipients, add Users and Groups to be exempted from the preset policies.
9. Select Next on each page until the Review and confirm your changes page.
10. On the Review and confirm your changes page, select Confirm.

Related links

• Defender admin center - Preset security policies
• CISA 15 Link Protection - MS.EXO.15.1
• CISA ScubaGear Rego Reference

Test Metadata

Field	Value
Test ID	CISA.MS.EXO.15.1
Severity	Medium
Suite	CISA
Category	exchange
PowerShell test	Test-MtCisaSafeLink
Tags	CISA, CISA.MS.EXO.15.1, MS.EXO, MS.EXO.15.1

Source

• Pester test: tests/cisa/exchange/Test-MtCisaSafeLink.Tests.ps1
• PowerShell source: powershell/public/cisa/exchange/Test-MtCisaSafeLink.ps1