Detection: Correlation by User and Risk

DEPRECATED DETECTION

This detection has been marked as deprecated by the Splunk Threat Research team. This means that it will no longer be maintained or supported. If you have any questions or concerns, please reach out to us at research@splunk.com.

Updated Date: 2024-10-17 ID: 610e12dc-b6fa-4541-825e-4a0b3b6f6773 Author: Patrick Bareiss, Splunk Type: Correlation Product: Splunk Enterprise Security

Description

The following analytic detects the correlation between the user and risk score and identifies users with a high risk score that pose a significant security risk such as unauthorized access attempts, suspicious behavior, or potential insider threats. Next, the analytic calculates the sum of the risk scores and groups the results by user, the corresponding signals, and the repository. The results are sorted in descending order based on the risk score and filtered to include records with a risk score greater than 80. Finally, the results are passed through a correlation filter specific to the user and risk. This detection is important because it identifies users who have a high risk score and helps to prioritize investigations and allocate resources. False positives might occur but the impact of such an attack can vary depending on the specific scenario such as data exfiltration, system compromise, or the disruption of critical services. Please investigate this notable event.

Search

1`risk_index` 
2| fillnull 
3| stats sum(risk_score) as risk_score values(source) as signals values(repository) as repository by user 
4| sort - risk_score 
5| where risk_score > 80 
6| `correlation_by_user_and_risk_filter`

Data Source

No data sources specified for this detection.

Macros Used

Name	Value
risk_index	`index=risk`
correlation_by_user_and_risk_filter	`search *`

correlation_by_user_and_risk_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
T1204.003	Malicious Image	Execution
T1204	User Execution	Execution

KillChainPhase.INSTALLATION

NistCategory.DE_AE

Cis18Value.CIS_13

TeamTNT

LAPSUS$

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	False

This configuration file applies to all detections of type Correlation. These correlations will generate Notable Events.

Implementation

For Dev Sec Ops POC

Known False Positives

unknown

Associated Analytic Story

Dev Sec Ops

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Correlation triggered for user $user$	70	70	100

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	Not Applicable	N/A	N/A	N/A
Unit	❌ Failing	N/A	`N/A`	`N/A`
Integration	❌ Failing	N/A	`N/A`	`N/A`

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: 2