Detection: Azure AD Multi-Factor Authentication Disabled

Updated Date: 2024-05-23 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.

Search

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	Supported App
Azure Active Directory Disable Strong Authentication	Azure	`'azure:monitor:aad'`	`'Azure AD'`	N/A

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

Azure Active Directory Account Takeover

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: 3