huntrule

Microsoft 365 Cloud App Security: Unusual Large Volume of File Deletion

Alerts when Microsoft 365 threat telemetry shows a user successfully deleting an unusually large number of files.

FreeReviewedSigma · Medium · v4
Product
m365
Service
threat_management
Author
austinsonger (SigmaHQ), DRL 1.1
Published
2021-08-19
Updated
2026-07-31
AnalysisDetection

ATT&CK techniques

Impact

  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Priv Esc

  7. Defense Evasion

  8. Cred Access

  9. Discovery

  10. Lateral Movement

  11. Collection

  12. C2

  13. Exfiltration

  14. Impact

What it detects

This rule flags cases where Microsoft Cloud App Security reports a successful event indicating a user deleted an unusually large volume of files. Attackers may attempt to disrupt services or destroy data, and high-volume deletions are a common impact pattern worth investigating. The detection relies on threat management telemetry from Microsoft 365 identifying the specific event source, event name, and successful status.

Reporting behind it

Related detections9 linkedT1485 — drag to rearrange
Suspicious Self-Deleting Batch Script Execution Consistent with Agonizing Serpens Wiper Cleanup
Malicious Mass Device Wipe via Intune Remote Actions (via m365)
Malicious S3 Bucket Deletion During Bling Libra Extortion
Malicious DYNOWIPER PowerShell Loader Execution (via ps_script)
Suspicious S3 Lifecycle Policy Set for Rapid Object Deletion
Malicious PathWiper Loader Script Execution from Windows Temp via WScript
Suspicious Free Space Wipe via cipher.exe
Suspicious sha256sum.exe Execution from Windows Temp Directory
Suspicious Secure Deletion of Free Space via Cipher (via process_creation)
Microsoft 365 Cloud App Security: Unusual Large Volume of File Deletion
Pivot detection · T1485 · 9 related

Changelog

v4
  1. v4
    Candidate ingested via manual entry.2026-07-31
  2. v3
    Candidate ingested via manual entry.2026-07-31
  3. v2
    Candidate ingested via manual entry.2026-07-31
  4. v1
    No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.