huntrule

Microsoft 365 Cloud App Security - Potential Ransomware Activity Alerts on File Upload

Flags successful Microsoft Cloud App Security reports of potential ransomware-related file uploads in Microsoft 365.

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 identifies events where Microsoft Cloud App Security reports “Potential ransomware activity” with a successful status. Such alerts matter because attackers may upload files that appear ransomware-infected to propagate malware or trigger downstream compromise. The detection relies on SecurityComplianceCenter threat management telemetry containing the event source, event name, and success status.

Reporting behind it

Related detections9 linkedT1486 — drag to rearrange
Malicious JADEPUFFER Lockd Encryptor Execution
Suspicious Mass Locked Extension File Creation by Ransomware
Malicious Interlock Ransomware Encrypted File and Note Creation (via file_event)
Malicious Ransomware Encryption Extension x2anylock
Malicious Fivehands Go Encryptor Execution via Command Line Flags
Malicious SafePay Ransomware Encryptor Command-Line Execution
Malicious The Gentlemen Ransomware Encryptor via Distinctive CLI Flags
Malicious GigaWiper Ransomware File Extension .candy
Malicious Forced BitLocker Encryption for Extortion (via process_creation)
Microsoft 365 Cloud App Security - Potential Ransomware Activity Alerts on File Upload
Pivot detection · T1486 · 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.