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
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 | 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`
The SPL above uses the following Macros:
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.
List of fields required to use this analytic.
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
Associated Analytic Story
|64.0||80||80||A suspicious registry modification to change the default icon association of windows to ransomware was detected on endpoint $dest$ by user $user$.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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