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Description

this search is to detect a suspicious registry modification to implement auto admin logon to a host. This technique was seen in BlackMatter ransomware to automatically logon to the compromise host after triggering a safemode boot to continue encrypting the whole network. This behavior is not a common practice and really a suspicious TTP or alert need to be consider if found within then network premise.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2023-03-29
  • Author: Steven Dick, Teoderick Contreras, Splunk
  • ID: d4a3eb62-0f1e-11ec-a971-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.AE
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= DefaultPassword OR Registry.registry_value_name= DefaultUserName) BY _time span=1h Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.dest Registry.registry_value_data Registry.process_guid 
| `drop_dm_object_name(Registry)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `add_defaultuser_and_password_in_registry_filter`

Macros

The SPL above uses the following Macros:

:information_source: add_defaultuser_and_password_in_registry_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
25.0 50 50 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: 4