Malicious S3 Object Encryption with Customer Provided Key via CopyObject

PremiumReviewedSigma · High · v1
Product
aws
Service
cloudtrail
Author
HuntRule
Published
2026-06-03
Updated
2026-08-28

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

What it detects

This rule detects S3 CopyObject or PutObject API calls that supply a customer provided SSE-C encryption key which is the technique used in the CopyObjection intrusion to encrypt a victim S3 bucket for ransom. Because the attacker holds the key AWS cannot recover the data making this a destructive extortion action. Detecting SSE-C on bulk object operations surfaces ransomware activity in cloud storage.

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INC Ransomware Ransom Note INC-README Written to Disk (via file_event)
Malicious DEVMAN Ransomware Encrypted File and Note Artifacts
Malicious S3 Object Encryption with Customer Provided Key via CopyObject
Pivot detection · T1486 · 9 related

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