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Description

The following analytic identifies the registration of a new Multi Factor authentication method for an AWS account. Adversaries who have obtained unauthorized access to an AWS account may register a new MFA method to maintain persistence.

  • Type: TTP

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2023-01-31
  • Author: Bhavin Patel, Splunk
  • ID: 4e3c26f2-4fb9-4bd7-ab46-1b76ffa2a23b

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1556 Modify Authentication Process Credential Access, Defense Evasion, Persistence
T1556.006 Multi-Factor Authentication Credential Access, Defense Evasion, Persistence
Kill Chain Phase
  • Exploitation
  • Installation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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 `cloudtrail` eventName=CreateVirtualMFADevice 
| stats count values(requestParameters.virtualMFADeviceName) as virtualMFADeviceName min(_time) as firstTime max(_time) as lastTime by eventSource aws_account_id errorCode userAgent eventID awsRegion userIdentity.principalId user_arn src_ip 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `aws_new_mfa_method_registered_for_user_filter`

Macros

The SPL above uses the following Macros:

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

Required fields

List of fields required to use this analytic.

  • src_ip
  • eventName
  • eventSource
  • requestParameters.virtualMFADeviceName
  • errorCode
  • userIdentity.principalId
  • userAgent
  • awsRegion
  • user_name
  • userIdentity.arn
  • _time

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.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 A new virtual device $virtualMFADeviceName$ is added to user $user_arn$

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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

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