O365 Email Transport Rule Changed
The following analytic identifies when a user with sufficient access to Exchange Online alters the mail flow/transport rule configuration of the organization. Transport rules are a set of rules that can be used by…
Description
The following analytic identifies when a user with sufficient access to Exchange Online alters the mail flow/transport rule configuration of the organization. Transport rules are a set of rules that can be used by attackers to modify or delete emails based on specific conditions, this activity could indicate an attacker hiding or exfiltrated data.
Detection logic
Detection requirements
- Platform
- LinuxmacOSOffice SuiteWindows
The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.
- Log source category
- office_365_universal_audit_log
Known benign triggers
- Legitimate administrative changes for business needs.
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 |
|---|---|
| attack.mitre.org/techniques/T1114/003/ | 4 |
| cardinalops.com/blog/cardinalops-contributes-new-mitre-attck-techniques-related-to-abuse-of-mail-transport-rules/ | Only this detection cites it |
| www.microsoft.com/en-us/security/blog/2022/09/22/malicious-OAuth-applications-used-to-compromise-email-servers-and-spread-spam/ | Only this detection cites it |
From the source
- At source
- Open at source
- Upstream identifier
- 11ebb7c2-46bd-41c9-81e1-d0b4b34583a2
- Tagged by the source as
- Data ExfiltrationOffice 365 Account TakeoverO365 TenantcloudSplunk CloudSplunk EnterpriseSplunk Enterprise Securitythreat
Licence
- Published under
- Apache License 2.0Read the licence
- Attribution
- Required
- Obtained under
- Apache-2.0Read the origin licence
Authorship
- Written by
- Published
- Aug 26, 2026
- Version
- 1