Detection: Windows Create Local Account

Updated Date: 2024-05-19 ID: 3fb2e8e3-7bc0-4567-9722-c5ab9f8595eb Author: Michael Haag, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects the creation of a new local user account on a Windows system. It leverages Windows Security Audit logs, specifically event ID 4720, to identify this activity. Monitoring the creation of local accounts is crucial for a SOC as it can indicate unauthorized access or lateral movement within the network. If confirmed malicious, this activity could allow an attacker to establish persistence, escalate privileges, or gain unauthorized access to sensitive systems and data.

1
2| tstats `security_content_summariesonly` values(All_Changes.result_id) as result_id count min(_time) as firstTime max(_time) as lastTime from datamodel=Change where All_Changes.result_id=4720 by All_Changes.user All_Changes.dest All_Changes.result All_Changes.action 
3| `drop_dm_object_name("All_Changes")` 
4| `security_content_ctime(lastTime)` 
5| `security_content_ctime(firstTime)` 
6| `windows_create_local_account_filter`

Data Source

Name Platform Sourcetype Source Supported App
N/A N/A N/A N/A N/A

Macros Used

Name Value
security_content_ctime convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)
windows_create_local_account_filter search *
windows_create_local_account_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
T1136.001 Local Account Persistence
T1136 Create Account Persistence
KillChainPhase.INSTALLATION
NistCategory.DE_AE
Cis18Value.CIS_10
APT3
APT39
APT41
APT5
Dragonfly
FIN13
Fox Kitten
Kimsuky
Leafminer
Magic Hound
TeamTNT
Wizard Spider
Indrik Spider
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 Risk Event True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

Implementation

This search requires you to have enabled your Group Management Audit Logs in your Local Windows Security Policy and be ingesting those logs. More information on how to enable them can be found here: http://whatevernetworks.com/auditing-group-membership-changes-in-active-directory/

Known False Positives

It is possible that an administrator created the account. Verifying activity with an administrator is advised. This analytic is set to anomaly to allow for risk to be added. Filter and tune as needed. Restrict to critical infrastructure to reduce any volume.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
The following $user$ was added to $dest$ as a local account. 18 20 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 XmlWinEventLog:Security XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Security XmlWinEventLog

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