AWS KMS Imported Key Material Usage — Sigma Rule

Rule metadata and linked tags

Author: toopricey. Source status: experimental; severity: high. Source dates: 2025-10-18 / not supplied.

{
  "product": "aws",
  "service": "cloudtrail"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 1f189644e9cd64ebe2b19bfb82c2f6ab523921adce89df64cd818884b6218792

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: AWS KMS Imported Key Material Usage
id: 1279262f-1464-422f-ac0d-5b545320c526
status: experimental
description: |
    Detects the import or deletion of key material in AWS KMS, which can be used as part of ransomware attacks. This activity is uncommon and provides a high certainty signal.
references:
    - https://www.chrisfarris.com/post/effective-aws-ransomware/
    - https://docs.aws.amazon.com/kms/latest/developerguide/ct-importkeymaterial.html
    - https://docs.aws.amazon.com/kms/latest/developerguide/ct-deleteimportedkeymaterial.html
author: toopricey
date: 2025-10-18
tags:
    - attack.impact
    - attack.t1486
    - attack.resource-development
    - attack.t1608.003
logsource:
    product: aws
    service: cloudtrail
detection:
    selection:
        eventSource: 'kms.amazonaws.com'
        eventName:
            - 'ImportKeyMaterial'
            - 'DeleteImportedKeyMaterial'
    condition: selection
falsepositives:
    - Legitimate use cases for imported key material are rare, but may include, Organizations with hybrid cloud architectures that import external key material for compliance requirements.
    - Development or testing environments that simulate external key management scenarios. Even in these cases, such activity is typically infrequent and should not add significant noise.
level: high

Original YAML and metadata in JSON

False positives

• Legitimate use cases for imported key material are rare, but may include, Organizations with hybrid cloud architectures that import external key material for compliance requirements.
• Development or testing environments that simulate external key management scenarios. Even in these cases, such activity is typically infrequent and should not add significant noise.

Source references

• https://www.chrisfarris.com/post/effective-aws-ransomware/
• https://docs.aws.amazon.com/kms/latest/developerguide/ct-importkeymaterial.html
• https://docs.aws.amazon.com/kms/latest/developerguide/ct-deleteimportedkeymaterial.html