IMPORTANT: No additional bug fixes or documentation updates
will be released for this version. For the latest information, see the
current release documentation.
O365 Exchange Suspicious Mailbox Right Delegation
editO365 Exchange Suspicious Mailbox Right Delegation
editIdentifies the assignment of rights to access content from another mailbox. An adversary may use the compromised account to send messages to other accounts in the network of the target organization while creating inbox rules, so messages can evade spam/phishing detection mechanisms.
Rule type: query
Rule indices:
- filebeat-*
- logs-o365*
Severity: low
Risk score: 21
Runs every: 5m
Searches indices from: None (Date Math format, see also Additional look-back time
)
Maximum alerts per execution: 100
References: None
Tags:
- Domain: Cloud
- Data Source: Microsoft 365
- Use Case: Configuration Audit
- Tactic: Persistence
Version: 102
Rule authors:
- Elastic
- Austin Songer
Rule license: Elastic License v2
Investigation guide
editRule query
editevent.dataset:o365.audit and event.provider:Exchange and event.action:Add-MailboxPermission and o365.audit.Parameters.AccessRights:(FullAccess or SendAs or SendOnBehalf) and event.outcome:success and not user.id : "NT AUTHORITY\SYSTEM (Microsoft.Exchange.Servicehost)"
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
-
Technique:
- Name: Account Manipulation
- ID: T1098
- Reference URL: https://attack.mitre.org/techniques/T1098/
-
Sub-technique:
- Name: Additional Email Delegate Permissions
- ID: T1098.002
- Reference URL: https://attack.mitre.org/techniques/T1098/002/