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Description

This analytic is developed to detect suspicious registry modification to change the default icon association of windows to ransomware . This technique was seen in Lockbit ransomware where it modified the default icon association of the compromised Windows OS host with its dropped ransomware icon file as part of its defacement payload. This registry is not commonly modified by a normal user so having this anomaly detection may help to catch possible lockbit ransomware infection or other malware.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2023-01-16
  • Author: Teoderick Contreras, Splunk
  • ID: a7a7afdb-3c58-45b6-9bff-63e5acfd9d40

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1112 Modify Registry Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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| 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.registry_path Registry.registry_key_name Registry.registry_value_name Registry.action Registry.dest  Registry.user 
| `security_content_ctime(lastTime)` 
| `security_content_ctime(firstTime)` 
| `drop_dm_object_name(Registry)` 
| `windows_modify_registry_default_icon_setting_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_modify_registry_default_icon_setting_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.user
  • Registry.registry_path
  • Registry.registry_key_name
  • Registry.registry_value_name
  • Registry.action

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

unknown

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 a registry $Registry.registry_path$ was modified or created to modify defaulticon settings of the $dest$

: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

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