Microsoft 365 Inbox Forwarding Rule Created
editMicrosoft 365 Inbox Forwarding Rule Created
editIdentifies 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.
Rule type: query
Rule indices:
- filebeat-*
- logs-o365*
Severity: medium
Risk score: 47
Runs every: 5m
Searches indices from: now-30m (Date Math format, see also Additional look-back time)
Maximum alerts per execution: 100
References:
- https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/responding-to-a-compromised-email-account?view=o365-worldwide
- https://docs.microsoft.com/en-us/powershell/module/exchange/new-inboxrule?view=exchange-ps
- https://docs.microsoft.com/en-us/microsoft-365/security/office-365-security/detect-and-remediate-outlook-rules-forms-attack?view=o365-worldwide
- https://raw.githubusercontent.com/PwC-IR/Business-Email-Compromise-Guide/main/Extractor%20Cheat%20Sheet.pdf
Tags:
- Domain: Cloud
- Data Source: Microsoft 365
- Use Case: Configuration Audit
- Tactic: Collection
Version: 206
Rule authors:
- Elastic
- Gary Blackwell
- Austin Songer
Rule license: Elastic License v2
Investigation guide
editSetup
editThe Office 365 Logs Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.
Rule query
editevent.dataset:o365.audit and event.provider:Exchange and
event.category:web and event.action:("New-InboxRule" or "Set-InboxRule") and
(
o365.audit.Parameters.ForwardTo:* or
o365.audit.Parameters.ForwardAsAttachmentTo:* or
o365.audit.Parameters.RedirectTo:*
)
and event.outcome:success
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Collection
- ID: TA0009
- Reference URL: https://attack.mitre.org/tactics/TA0009/
-
Technique:
- Name: Email Collection
- ID: T1114
- Reference URL: https://attack.mitre.org/techniques/T1114/
-
Sub-technique:
- Name: Email Forwarding Rule
- ID: T1114.003
- Reference URL: https://attack.mitre.org/techniques/T1114/003/