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 Delegationedit
Identifies the assignment of rights to accesss content from another mailbox. An adversary may use the compromised account to send messages to other accounts in the network of the target business 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: 5 minutes
Searches indices from: now-6m (Date Math format, see also Additional look-back time
)
Maximum alerts per execution: 100
Tags:
- Elastic
- Cloud
- Microsoft 365
- Continuous Monitoring
- SecOps
- Configuration Audit
Version: 1
Added (Elastic Stack release): 7.16.0
Rule authors: Elastic, Austin Songer
Rule license: Elastic License v2
Potential false positivesedit
Assignment of rights to a service account.
Investigation guideedit
## Config The Microsoft 365 Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule.
Rule queryedit
event.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
Threat mappingedit
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/