Detection: Azure AD Multi-Factor Authentication Disabled

Updated Date: 2024-09-30 ID: 482dd42a-acfa-486b-a0bb-d6fcda27318e Author: Mauricio Velazco, Gowthamaraj Rajendran, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects attempts to disable multi-factor authentication (MFA) for an Azure AD user. It leverages Azure Active Directory AuditLogs to identify the "Disable Strong Authentication" operation. This activity is significant because disabling MFA can allow adversaries to maintain persistence using compromised accounts without raising suspicion. If confirmed malicious, this action could enable attackers to bypass an essential security control, potentially leading to unauthorized access and prolonged undetected presence in the environment.

1`azure_monitor_aad` category=AuditLogs operationName="Disable Strong Authentication" 
2| rename properties.* as * 
3| rename targetResources{}.type as type 
4| rename initiatedBy.user.userPrincipalName as initiatedBy 
5| stats count min(_time) as firstTime max(_time) as lastTime by user, type, operationName, initiatedBy, result 
6| `security_content_ctime(firstTime)` 
7| `security_content_ctime(lastTime)` 
8| `azure_ad_multi_factor_authentication_disabled_filter`

Data Source

Name Platform Sourcetype Source
Azure Active Directory Disable Strong Authentication Azure icon Azure 'azure:monitor:aad' 'Azure AD'

Macros Used

Name Value
azure_monitor_aad sourcetype=azure:monitor:aad
azure_ad_multi_factor_authentication_disabled_filter search *
azure_ad_multi_factor_authentication_disabled_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
T1586 Compromise Accounts Resource Development
T1586.003 Cloud Accounts Resource Development
T1556 Modify Authentication Process Credential Access
T1556.006 Multi-Factor Authentication Defense Evasion
KillChainPhase.EXPLOITAITON
KillChainPhase.INSTALLATION
KillChainPhase.WEAPONIZATION
NistCategory.DE_CM
Cis18Value.CIS_10
APT29
FIN13
Scattered Spider

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 Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

You must install the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase (https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Active Directory events into your Splunk environment through an EventHub. This analytic was written to be used with the azure:monitor:aad sourcetype leveraging the AuditLogs log category.

Known False Positives

Legitimate use case may require for users to disable MFA. Filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
MFA disabled for User $user$ initiated by $initiatedBy$ 45 50 90
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset Azure AD azure:monitor:aad
Integration ✅ Passing Dataset Azure AD azure:monitor:aad

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: 4