Senders are not being allow listed in an unsafe manner

Contributed by Michael SouleAll contributors →

Part of ORCA · Defender · Anti-spam · All checks

Run this check

Invoke-Maester -TestId ORCA.109

Overview

Emails coming from allow listed senders bypass several layers of protection within Exchange Online Protection. If senders are allow listed, they are open to being spoofed from malicious actors.

Remediation action

Remove allow listing on senders.

Related Links

• Microsoft 365 Defender Portal - Anti-spam settings
• Recommended settings for EOP and Office 365 Microsoft Defender for Office 365 security
• Use Anti-Spam Policy Sender/Domain Allow lists

Details

Every attribute of this check

Field	Value
Test ID	ORCA.109
Severity	Medium
Suite	ORCA
Product	Defender
Related products	Exchange Online
Feature	Anti-spam
Area	Email and collaboration protection
Resource type	Policy
User impact	Low
Implementation cost	Medium
MITRE ATT&CK	T1566 Phishing, T1684.002 Email Spoofing
Supports controls	nist-800-53-r5:SI-8
PowerShell test	Test-ORCA109
Services	ExchangeOnline

Source

• Test: tests/orca/Test.ORCA.109.ps1
• Documentation: tests/orca/Test.ORCA.109.md