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Description

The following analytic identifies instances where Multi-Factor Authentication (MFA) is disabled for a user within the Office 365 environment. It leverages O365 audit logs, specifically focusing on events related to MFA settings. Disabling MFA removes a critical security layer, making accounts more vulnerable to unauthorized access. If confirmed malicious, this activity could indicate an attacker attempting to maintain persistence or an insider threat, significantly increasing the risk of unauthorized access. Immediate investigation is required to validate the reason for disabling MFA, potentially re-enable it, and assess any other suspicious activities related to the affected account.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Authentication
  • Last Updated: 2024-05-11
  • Author: Rod Soto, Splunk
  • ID: c783dd98-c703-4252-9e8a-f19d9f5c949e

Annotations

ATT&CK

ATT&CK

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


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`o365_management_activity` Operation="Disable Strong Authentication." 
| stats count earliest(_time) as firstTime latest(_time) as lastTime by UserType Operation UserId ResultStatus object 
| rename UserType AS user_type, Operation AS action, UserId AS src_user, object AS user, ResultStatus AS result 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `o365_disable_mfa_filter`

Macros

The SPL above uses the following Macros:

:information_source: o365_disable_mfa_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.

  • _time
  • Operation
  • UserType
  • user
  • status
  • signature
  • dest
  • ResultStatus

How To Implement

You must install the Splunk Microsoft Office 365 add-on. This search works with o365:management:activity

Known False Positives

Unless it is a special case, it is uncommon to disable MFA or Strong Authentication

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 User $src_user$ has executed an operation $action$ for user $user$

: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: 3