Suspicious Mail Send via Microsoft Graph by Application Identity via M365 Audit
- Product
- m365
- Service
- audit
- Author
- HuntRule
- Published
- 2026-05-09
- Updated
- 2026-08-28
ATT&CK techniques
Lateral MovementRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule detects mail sent through the Microsoft Graph sendMail action by an application or agent identity, the delivery step an attacker uses after hijacking an Entra assistive agent to send internal spearphishing. Because agents that gain send-mail access can distribute malicious links from a trusted internal identity, Graph-driven mail sends attributed to service principals should be reviewed against recent consent grants.
Reporting behind it
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
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Also included
Unlocked rules convert on this page — to Splunk SPL or Splunk — Raw Index SPL or Microsoft Sentinel KQL or Microsoft Sentinel ASIM ASIM KQL or Microsoft Defender XDR KQL or Elastic Security KQL or Elastic Security Lucene or Elastic Security ES|QL or CrowdStrike Falcon CQL or SentinelOne PowerQuery or Palo Alto Cortex XDR XQL or Carbon Black Cloud Platform Search or Carbon Black EDR Process Search or Google Security Operations UDM Search or IBM QRadar AQL or Sumo Logic Cloud SIEM Rules expression or Rapid7 InsightIDR LEQL or Graylog Search or OpenSearch Lucene or OpenSearch PPL PPL or Grafana Loki LogQL or SQLite SQL or Zircolite SQLite — with the log-source profile the engine picked, the field map it used, and everything it could not express. Converting a rule you have unlocked costs no further credit.