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Description

The following analytic identifies the registration of a new Multi Factor authentication method for an AWS account logged through Amazon Secruity Lake (ASL). 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: 2023-05-22
  • Author: Patrick Bareiss, Splunk
  • ID: 33ae0931-2a03-456b-b1d7-b016c5557fbd

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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 `amazon_security_lake` api.operation=CreateVirtualMFADevice 
| stats count min(_time) as firstTime max(_time) as lastTime by api.operation api.service.name identity.user.account_uid identity.user.credential_uid identity.user.name identity.user.type identity.user.uid identity.user.uuid http_request.user_agent src_endpoint.ip cloud.region 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `asl_aws_new_mfa_method_registered_for_user_filter`

Macros

The SPL above uses the following Macros:

:information_source: asl_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.

  • api.service.name
  • api.operation
  • identity.user.account_uid
  • identity.user.credential_uid
  • identity.user.name
  • identity.user.type
  • identity.user.uid
  • identity.user.uuid
  • http_request.user_agent
  • src_endpoint.ip

How To Implement

You must install Splunk Add-On for AWS Version v7.0.0 (https://splunkbase.splunk.com/app/1876) that includes includes a merge of all the capabilities of the Splunk Add-on for Amazon Security Lake. This search works with Amazon Security Lake logs which are parsed in the Open Cybersecurity Schema Framework (OCSF)format.

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 is added to user $identity.user.name$

: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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