ORCA.118.4: Your own domains are not being allow listed in an unsafe manner in Transport Rules.
| ID | ORCA.118.4 |
| Severity | High |
| Suite | ORCA |
| Product | Defender |
| Related products | Exchange Online |
| Feature | Mail flow |
| Security area | Email and collaboration protection |
| Resource type | MailFlowRule |
| User impact of fixing | Low |
| Effort to fix | Medium |
| Framework controls | nist-800-53-r5:SI-8 Spam Protection |
| MITRE ATT&CK | T1566, T1684.002 |
| Reads from | Exchange Online |
What this checks and how to fix it
Section titled “What this checks and how to fix it”Emails coming from allow listed domains bypass several layers of protection within Exchange Online Protection. When allow listing your own domains, an attacker can spoof any account in your organisation that has this domain. This is a significant phishing attack vector.
Remediation action
Section titled “Remediation action”Remove allow listing on domains belonging to your organisation.
Related Links
Section titled “Related Links”- Exchange admin center in Exchange Online
- Using Exchange Transport Rules (ETRs) to allow specific senders
Mito check, based on ORCA. Author: thomas-s-schmidt. Open-source licences.
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