M365 Exchange Mail Flow Transport Rule Created
Identifies a transport rule creation in Microsoft 365. As a best practice, Exchange Online mail transport rules should not be set to forward email to domains outside of your organization. An adversary may create…
Description
Identifies a transport rule creation in Microsoft 365. As a best practice, Exchange Online mail transport rules should not be set to forward email to domains outside of your organization. An adversary may create transport rules to exfiltrate data.
Detection logic
Its licence does not clear it for publishing here
Sunturai publishes a detection's own text where the licence it arrived under has been reviewed and permits it, and Elastic License 2.0 has not. The query as its source wrote it, its canonical form and the hash that pins this revision are in the workspace record.
Detection requirements
- Platform
- IaaSLinuxmacOSOffice SuiteSaaSWindows
The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.
- Log source category
- event_index
Known benign triggers
- A new transport rule may be created by a system or network administrator. Verify that the configuration change was expected. Exceptions can be added to this rule to filter expected behavior.
MITRE ATT&CK mappings
0 exclusive techniques.This is coverage no other published rule has; it is not this rule's total technique count.
References
| Reference | Cited by |
|---|---|
| docs.microsoft.com/en-us/exchange/security-and-compliance/mail-flow-rules/mail-flow-rules | 2 |
| docs.microsoft.com/en-us/powershell/module/exchange/new-transportrule?view=exchange-ps | Only this detection cites it |
From the source
- At source
- Open at source
- Upstream identifier
- ff4dd44a-0ac6-44c4-8609-3f81bc820f02
- Tagged by the source as
- Data Source: Microsoft 365Data Source: Microsoft 365 Audit LogsDomain: CloudDomain: EmailDomain: SaaSNoise: LowPerformance: NormalPlatform: Microsoft 365Resources: Investigation GuideRule Type: Custom Query (KQL)Service: Microsoft Exchange OnlineTactic: ExfiltrationUse Case: Configuration Audit
Licence
- Published under
- Elastic License 2.0Read the licence
- Attribution
- Required
Authorship
- Written by
- Published
- Sep 20, 2026
- Version
- 3