Detection: AWS New MFA Method Registered For User

Updated Date: 2026-05-13 ID: 4e3c26f2-4fb9-4bd7-ab46-1b76ffa2a23b Author: Bhavin Patel, Splunk Type: TTP Product: Splunk Enterprise Security

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.

Search

 1`cloudtrail` eventName=CreateVirtualMFADevice
 2  
 3| rename userName as user
 4  
 5| stats count min(_time) as firstTime max(_time) as lastTime
 6    BY signature dest user
 7       user_agent src vendor_account
 8       vendor_region vendor_product
 9  
10| `security_content_ctime(firstTime)`
11  
12| `security_content_ctime(lastTime)`
13  
14| `aws_new_mfa_method_registered_for_user_filter`

Data Source

Name	Platform	Sourcetype	Source
AWS CloudTrail CreateVirtualMFADevice	AWS	`'aws:cloudtrail'`	`'aws_cloudtrail'`

Macros Used

Name	Value
cloudtrail	`sourcetype=aws:cloudtrail`
aws_new_mfa_method_registered_for_user_filter	`search *`

aws_new_mfa_method_registered_for_user_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1556.006	Multi-Factor Authentication	Credential Access

Exploitation

Installation

DE.CM

CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Finding (Notable)	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Intermediate Finding (Risk Event)	No

TTP detections generate a Finding (Notable) and may generate Intermediate Findings (Risk Events) for associated entities.

Implementation

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.

Associated Analytic Story

AWS Identity and Access Management Account Takeover

Finding

Title	Entity Field	Entity Type	Risk Score
A new virtual device is added to user $user$	user	user	50

Threat Objects

Field	Type
src	ip_address

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`aws_cloudtrail`	`aws:cloudtrail`
Integration	✅ Passing	Dataset	`aws_cloudtrail`	`aws:cloudtrail`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 12