Windows Modify Registry Default Icon Setting

name: Windows Modify Registry Default Icon Setting
id: a7a7afdb-3c58-45b6-9bff-63e5acfd9d40
version: 10
date: '2026-03-10'
author: Teoderick Contreras, Splunk
status: production
type: Anomaly
description: The following analytic detects suspicious modifications to the Windows registry's default icon settings, a technique associated with Lockbit ransomware. It leverages data from the Endpoint Registry data model, focusing on changes to registry paths under "*HKCR\\*\\defaultIcon\\(Default)*". This activity is significant as it is uncommon for normal users to modify these settings, and such changes can indicate ransomware infection or other malware. If confirmed malicious, this could lead to system defacement and signal a broader ransomware attack, potentially compromising sensitive data and system integrity.
data_source:
    - Sysmon EventID 13
search: '| tstats `security_content_summariesonly` count  min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Registry where Registry.registry_path ="*\\defaultIcon\\(Default)*" Registry.registry_path = "*HKCR\\*" by Registry.action Registry.dest Registry.process_guid Registry.process_id Registry.registry_hive Registry.registry_path Registry.registry_key_name Registry.registry_value_data Registry.registry_value_name Registry.registry_value_type Registry.status Registry.user Registry.vendor_product | `security_content_ctime(lastTime)` | `security_content_ctime(firstTime)` | `drop_dm_object_name(Registry)` | `windows_modify_registry_default_icon_setting_filter`'
how_to_implement: To successfully implement this search, you must be ingesting data that records registry activity from your hosts to populate the endpoint data model in the registry node. This is typically populated via endpoint detection-and-response product, such as Carbon Black or endpoint data sources, such as Sysmon. The data used for this search is typically generated via logs that report reads and writes to the registry.
known_false_positives: No false positives have been identified at this time.
references:
    - https://blogs.vmware.com/security/2022/10/lockbit-3-0-also-known-as-lockbit-black.html
    - https://news.sophos.com/en-us/2020/04/24/lockbit-ransomware-borrows-tricks-to-keep-up-with-revil-and-maze/
drilldown_searches:
    - name: View the detection results for - "$dest$" and "$user$"
      search: '%original_detection_search% | search  dest = "$dest$" user = "$user$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$" and "$user$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$", "$user$") starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: A suspicious registry modification to change the default icon association of windows to ransomware was detected on endpoint $dest$ by user $user$.
    risk_objects:
        - field: dest
          type: system
          score: 20
        - field: user
          type: user
          score: 20
    threat_objects: []
tags:
    analytic_story:
        - LockBit Ransomware
    asset_type: Endpoint
    mitre_attack_id:
        - T1112
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/lockbit_ransomware/sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog