Detection: Disabling Windows Local Security Authority Defences via Registry

Description

The following analytic identifies the deletion of registry keys that disable Local Security Authority (LSA) protection and Microsoft Defender Device Guard. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on registry actions and paths associated with LSA and Device Guard settings. This activity is significant because disabling these defenses can leave a system vulnerable to various attacks, including credential theft and unauthorized code execution. If confirmed malicious, this action could allow attackers to bypass critical security mechanisms, leading to potential system compromise and persistent access.

Search

1
2| tstats `security_content_summariesonly` min(_time) as _time from datamodel=Endpoint.Registry where Registry.registry_path IN ("*\\SYSTEM\\CurrentControlSet\\Control\\Lsa\\LsaCfgFlags", "*\\SOFTWARE\\Policies\\Microsoft\\Windows\\DeviceGuard\\*", "*\\SYSTEM\\CurrentControlSet\\Control\\Lsa\\RunAsPPL") Registry.action IN (deleted, unknown) by Registry.action Registry.registry_path Registry.process_guid Registry.dest Registry.user
3| `drop_dm_object_name(Registry)` 
4| join type=outer process_guid [
5| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes by Processes.user Processes.process_name Processes.process Processes.dest Processes.parent_process_name Processes.parent_process Processes.process_guid 
6| `drop_dm_object_name(Processes)`] 
7| table _time action dest user parent_process_name parent_process process_name process process_guid registry_path 
8| `disabling_windows_local_security_authority_defences_via_registry_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Sysmon EventID 1	Windows	'xmlwineventlog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'	N/A

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Potential to be triggered by an administrator disabling protections for troubleshooting purposes.

Associated Analytic Story

• Windows Defense Evasion Tactics

• Windows Registry Abuse

Risk Based Analytics (RBA)

References

• https://docs.microsoft.com/en-us/windows-server/security/credentials-protection-and-management/configuring-additional-lsa-protection

• https://docs.microsoft.com/en-us/windows/security/identity-protection/credential-guard/credential-guard-manage

Detection Testing

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: GitHub | Version: 3