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Description

The following analytic identifies a modification in the Windows registry to disable windows defender phishing filter. This setting controls whether users can manually disable or modify the browser's built-in phishing filter. When attackers modify "PreventOverride" to 0, it might indicate an attempt to disable the prevention of user overrides for the phishing filter within Microsoft Edge. This change allows users to bypass or disable the built-in phishing protection provided by the browser. By allowing users to override the phishing filter, attackers may attempt to deceive users into visiting phishing websites or malicious pages without triggering warnings or protections from the browser's built-in security measures. This manipulation increases the risk of users unknowingly accessing potentially harmful websites, leading to potential security incidents or compromises.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-01-08
  • Author: Teoderick Contreras, Splunk
  • ID: 10ca081c-57b1-4a78-ba56-14a40a7e116a

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 min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Registry where Registry.registry_key_name = "*\\MicrosoftEdge\\PhishingFilter" Registry.registry_value_name IN ("EnabledV9", "PreventOverride") Registry.registry_value_data="0x00000000" by Registry.registry_key_name Registry.user Registry.registry_path Registry.registry_value_data Registry.action Registry.dest 
| `drop_dm_object_name(Registry)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_impair_defense_overide_win_defender_phishing_filter_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_impair_defense_overide_win_defender_phishing_filter_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 Phishing Filter registry was modified 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: 1