Detection: Azure Active Directory High Risk Sign-in

Updated Date: 2024-05-22 ID: 1ecff169-26d7-4161-9a7b-2ac4c8e61bea Author: Mauricio Velazco, Gowthamaraj Rajendran, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects high-risk sign-in attempts against Azure Active Directory, identified by Azure Identity Protection. It leverages the RiskyUsers and UserRiskEvents log categories from Azure AD events ingested via EventHub. This activity is significant as it indicates potentially compromised accounts, flagged by heuristics and machine learning. If confirmed malicious, attackers could gain unauthorized access to sensitive resources, leading to data breaches or further exploitation within the environment.

Search

1 `azure_monitor_aad` category=UserRiskEvents properties.riskLevel=high 
2| rename properties.* as * 
3| stats count min(_time) as firstTime max(_time) as lastTime values(user) as user by src_ip, activity, riskLevel, riskEventType, additionalInfo 
4| `security_content_ctime(firstTime)` 
5| `security_content_ctime(lastTime)` 
6| `azure_active_directory_high_risk_sign_in_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Azure Active Directory	Azure	`'azure:monitor:aad'`	`'Azure AD'`	N/A

Macros Used

Name	Value
azure_monitor_aad	`sourcetype=azure:monitor:aad`
azure_active_directory_high_risk_sign_in_filter	`search *`

azure_active_directory_high_risk_sign_in_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
T1110	Brute Force	Credential Access
T1110.003	Password Spraying	Credential Access

KillChainPhase.EXPLOITAITON

KillChainPhase.WEAPONIZATION

NistCategory.DE_CM

Cis18Value.CIS_10

APT29

APT28

APT38

APT39

DarkVishnya

Dragonfly

FIN5

Fox Kitten

HEXANE

OilRig

Turla

APT28

APT29

APT33

Chimera

HEXANE

Lazarus Group

Leafminer

Silent Librarian

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. Specifically, this analytic leverages the RiskyUsers and UserRiskEvents log category in the azure:monitor:aad sourcetype.

Known False Positives

Details for the risk calculation algorithm used by Identity Protection are unknown and may be prone to false positives.

Associated Analytic Story

Azure Active Directory Account Takeover

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
A high risk event was identified by Identify Protection for user $user$	54	60	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