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Description

The following analytic detects modifications to the Windows registry that override the Windows Defender SmartScreen prompt. It leverages data from the Endpoint.Registry data model, specifically monitoring changes to the "PreventSmartScreenPromptOverride" registry setting. This activity is significant because it indicates an attempt to disable the prevention of user overrides for SmartScreen prompts, potentially allowing users to bypass security warnings. If confirmed malicious, this could lead to users inadvertently executing or accessing harmful content, increasing the risk of security incidents or system compromises.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-05-31
  • Author: Teoderick Contreras, Splunk
  • ID: 08058866-7987-486f-b042-275715ef6e9d

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1562.001 Disable or Modify Tools Defense Evasion
T1562 Impair Defenses Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Registry WHERE Registry.registry_path= "*\\Microsoft\\Edge\\PreventSmartScreenPromptOverride" Registry.registry_value_data= "0x00000000" BY _time span=1h Registry.dest Registry.user Registry.registry_path Registry.registry_key_name Registry.registry_value_name Registry.registry_value_data Registry.process_guid 
| `drop_dm_object_name(Registry)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_impair_defense_override_smartscreen_prompt_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_impair_defense_override_smartscreen_prompt_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.registry_key_name
  • Registry.registry_value_name
  • Registry.dest
  • Registry.user
  • Registry.registry_path
  • Registry.action

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Registry node.

Known False Positives

It is unusual to turn this feature off a Windows system since it is a default security control, although it is not rare for some policies to disable it. Although no false positives have been identified, use the provided filter macro to tune the search.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
49.0 70 70 Windows Defender SmartScreen prompt was override on $dest$.

: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

source | version: 2