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Description

The following analytic detects a suspicious registry modification that enables auto admin logon on a host. It leverages data from the Endpoint.Registry data model, specifically looking for changes to the "AutoAdminLogon" value within the "SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" registry path. This activity is significant because it was observed in BlackMatter ransomware attacks to maintain access after a safe mode reboot, facilitating further encryption. If confirmed malicious, this could allow attackers to automatically log in and continue their operations, potentially leading to widespread network encryption and data loss.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-05-10
  • Author: Steven Dick, Teoderick Contreras, Splunk
  • ID: 1379d2b8-0f18-11ec-8ca3-acde48001122

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1552.002 Credentials in Registry Credential Access
T1552 Unsecured Credentials Credential Access
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Registry WHERE (Registry.registry_path= "*SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Winlogon*" AND Registry.registry_value_name=AutoAdminLogon AND Registry.registry_value_data=1) BY _time span=1h Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.registry_value_data Registry.process_guid Registry.dest 
| `drop_dm_object_name(Registry)` 
| where isnotnull(registry_value_data) 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `auto_admin_logon_registry_entry_filter`

Macros

The SPL above uses the following Macros:

:information_source: auto_admin_logon_registry_entry_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Registry.dest
  • Registry.registry_value_name
  • Registry.registry_key_name
  • Registry.registry_path
  • Registry.registry_value_data
  • Registry.process_guid

How To Implement

To successfully implement this search, you need to be ingesting logs with the registry value name, registry path, and registry value data from your endpoints. If you are using Sysmon, you must have at least version 2.0 of the offical Sysmon TA. https://splunkbase.splunk.com/app/5709

Known False Positives

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
63.0 70 90 modified registry key $registry_key_name$ with registry value $registry_value_name$ to prepare autoadminlogon

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

Reference

Test Dataset

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 | version: 5