ASL AWS New MFA Method Registered For User

name: ASL AWS New MFA Method Registered For User
id: 33ae0931-2a03-456b-b1d7-b016c5557fbd
version: 14
creation_date: '2023-01-31'
modification_date: '2026-05-13'
author: Patrick Bareiss, Splunk
status: production
type: TTP
description: The following analytic identifies the registration of a new Multi-Factor Authentication (MFA) method for an AWS account, as logged through Amazon Security Lake (ASL). It detects this activity by monitoring the `CreateVirtualMFADevice` API operation within ASL logs. This behavior is significant because adversaries who gain unauthorized access to an AWS account may register a new MFA method to maintain persistence. If confirmed malicious, this activity could allow attackers to secure their access, making it harder to detect and remove their presence from the compromised environment.
data_source:
    - ASL AWS CloudTrail
search: |-
    `amazon_security_lake` api.operation=CreateVirtualMFADevice
      | fillnull
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY actor.user.uid api.operation api.service.name
           http_request.user_agent src_endpoint.ip actor.user.account.uid
           cloud.provider cloud.region
      | rename actor.user.uid as user api.operation as action api.service.name as dest http_request.user_agent as user_agent src_endpoint.ip as src actor.user.account.uid as vendor_account cloud.provider as vendor_product cloud.region as vendor_region
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `asl_aws_new_mfa_method_registered_for_user_filter`
how_to_implement: The detection is based on Amazon Security Lake events from Amazon Web Services (AWS), which is a centralized data lake that provides security-related data from AWS services. To use this detection, you must ingest CloudTrail logs from Amazon Security Lake into Splunk. To run this search, ensure that you ingest events using the latest version of Splunk Add-on for Amazon Web Services (https://splunkbase.splunk.com/app/1876) or the Federated Analytics App.
known_false_positives: Newly onboarded users who are registering an MFA method for the first time will also trigger this detection.
references:
    - https://aws.amazon.com/blogs/security/you-can-now-assign-multiple-mfa-devices-in-iam/
    - https://attack.mitre.org/techniques/T1556/
    - https://attack.mitre.org/techniques/T1556/006/
    - https://twitter.com/jhencinski/status/1618660062352007174
finding:
    title: A new virtual device is added to user $user$
    entity:
        field: user
        type: user
        score: 50
threat_objects:
    - field: src
      type: ip_address
analytic_story:
    - AWS Identity and Access Management Account Takeover
asset_type: AWS Account
mitre_attack_id:
    - T1556.006
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: cloud
security_domain: identity