MediumElastic detection rules Elastic +3

M365 Exchange Inbox Forwarding Rule Created

Description

Identifies when a new Inbox forwarding rule is created in Microsoft 365. Inbox rules process messages in the Inbox based on conditions and take actions. In this case, the rules will forward the emails to a defined address. Attackers can abuse Inbox Rules to intercept and exfiltrate email data without making organization-wide configuration changes or having the corresponding privileges.

Detection logic

Its licence does not clear it for publishing here

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Detection requirements

Platform: Linux macOS Office Suite Windows
The rule states no platform. This is derived from the ATT&CK technique it maps to.
Log source category: event_index

Known benign triggers

Users and Administrators can create inbox rules for legitimate purposes. Verify if it complies with the company policy and done with the user's consent. Exceptions can be added to this rule to filter expected behavior.

References

Links the source published beside this detection. Reference is the link the source wrote, unmodified. Class is decided by this catalogue from the host and path, not stated by the source. Cited by counts published detections citing the same resource, including this one, and the sources beneath it count the repositories this catalogue ingests, which is not the same as independent research.
Reference	Class	Cited by
docs.microsoft.com/en-us/microsoft-365/security/office-365-security/detect-and-remediate-outlook-rules-forms-attack?view=o365-worldwide	Product documentation	Only this detection cites it
docs.microsoft.com/en-us/microsoft-365/security/office-365-security/responding-to-a-compromised-email-account?view=o365-worldwide	Product documentation	Only this detection cites it
docs.microsoft.com/en-us/powershell/module/exchange/new-inboxrule?view=exchange-ps	Product documentation	Only this detection cites it
raw.githubusercontent.com/PwC-IR/Business-Email-Compromise-Guide/main/Extractor%20Cheat%20Sheet.pdf	Unclassified	Only this detection cites it
www.microsoft.com/en-us/security/blog/2026/04/06/ai-enabled-device-code-phishing-campaign-april-2026/	Threat report	2

Detection rules

M365 Exchange Inbox Forwarding Rule Created

Description

Detection logic

Detection requirements

Known benign triggers

MITRE ATT&CK mappings

References

From the source

Licence

Authorship

Detection rules