splunk_escuTTP

AWS New MFA Method Registered For User

The following analytic detects the registration of a new Multi-Factor Authentication (MFA) method for an AWS account. It leverages AWS CloudTrail logs to identify the `CreateVirtualMFADevice` event. This activity 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 could allow attackers to secure their access, making it difficult to detect and remove their presence, potentially leading to further unauthorized activities and data breaches.

Detection Query

`cloudtrail` eventName=CreateVirtualMFADevice
  | rename userName as user
  | stats count min(_time) as firstTime max(_time) as lastTime
    BY signature dest user
       user_agent src vendor_account
       vendor_region vendor_product
  | `security_content_ctime(firstTime)`
  | `security_content_ctime(lastTime)`
  | `aws_new_mfa_method_registered_for_user_filter`

Author

Bhavin Patel, Splunk

Data Sources

AWS CloudTrail CreateVirtualMFADevice

References

Raw Content

name: AWS New MFA Method Registered For User
id: 4e3c26f2-4fb9-4bd7-ab46-1b76ffa2a23b
version: 12
creation_date: '2023-01-31'
modification_date: '2026-05-13'
author: Bhavin Patel, Splunk
status: production
type: TTP
description: The following analytic detects the registration of a new Multi-Factor Authentication (MFA) method for an AWS account. It leverages AWS CloudTrail logs to identify the `CreateVirtualMFADevice` event. This activity 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 could allow attackers to secure their access, making it difficult to detect and remove their presence, potentially leading to further unauthorized activities and data breaches.
data_source:
    - AWS CloudTrail CreateVirtualMFADevice
search: |-
    `cloudtrail` eventName=CreateVirtualMFADevice
      | rename userName as user
      | stats count min(_time) as firstTime max(_time) as lastTime
        BY signature dest user
           user_agent src vendor_account
           vendor_region vendor_product
      | `security_content_ctime(firstTime)`
      | `security_content_ctime(lastTime)`
      | `aws_new_mfa_method_registered_for_user_filter`
how_to_implement: You must install Splunk AWS add on and Splunk App for AWS. This search works when AWS CloudTrail logs.
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
drilldown_searches:
    - name: View the detection results for - "$user$"
      search: '%original_detection_search% | search  user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
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
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1556.006/aws_new_mfa_method_registered_for_user/cloudtrail.json
          sourcetype: aws:cloudtrail
          source: aws_cloudtrail
      test_type: unit