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Description

The following analytic identifies an attempt to disable multi-factor authentication for an AWS IAM user. An adversary who has obtained access to an AWS tenant may disable multi-factor authentication as a way to plant a backdoor and maintain persistence using a valid account. This way the attackers can keep persistance in the environment without adding new users.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2022-10-04
  • Author: Bhavin Patel, Splunk
  • ID: 374832b1-3603-420c-b456-b373e24d34c0

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1586 Compromise Accounts Resource Development
T1586.003 Cloud Accounts Resource Development
T1621 Multi-Factor Authentication Request Generation Credential Access
T1556 Modify Authentication Process Credential Access, Defense Evasion, Persistence
T1556.006 Multi-Factor Authentication Credential Access, Defense Evasion, Persistence
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 3
  • CIS 5
  • CIS 16
CVE
1
2
3
4
5
`cloudtrail` (eventName= DeleteVirtualMFADevice OR eventName=DeactivateMFADevice) 
| stats count min(_time) as firstTime max(_time) as lastTime by src eventName eventSource aws_account_id userAgent eventID awsRegion user_name userIdentity.arn status 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `aws_multi_factor_authentication_disabled_filter`

Macros

The SPL above uses the following Macros:

:information_source: aws_multi-factor_authentication_disabled_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
  • eventName
  • eventSource
  • aws_account_id
  • errorCode
  • errorMessage
  • userAgent
  • eventID
  • awsRegion
  • user_name
  • userIdentity.arn

How To Implement

The Splunk AWS Add-on is required to utilize this data. The search requires AWS Cloudtrail logs.

Known False Positives

AWS Administrators may disable MFA but it is highly unlikely for this event to occur without prior notice to the company

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 User $user_name$ has disabled Multi-Factor authentication for AWS account $aws_account_id$

: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

source | version: 1