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Description

The following analytic identifies a modification in the Windows registry to disable Windows Defender web content evaluation. The "EnableWebContentEvaluation" registry entry typically relates to security settings within Microsoft Edge or Internet Explorer, enabling the evaluation of web content for security purposes. When attackers modify "EnableWebContentEvaluation" to 0, they might attempt to disable the browser's capability to evaluate web content for security purposes. Disabling this feature could potentially impact the browser's ability to assess the security risks associated with web content, such as potentially malicious scripts, active content, or unsafe web elements. By turning off content evaluation, attackers might aim to exploit security vulnerabilities present in web content without triggering security warnings or blocks. This manipulation increases the risk of users accessing or interacting with malicious content, potentially leading to security compromises or system exploitation.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint, Web
  • Last Updated: 2024-01-08
  • Author: Teoderick Contreras, Splunk
  • ID: e234970c-dcf5-4f80-b6a9-3a562544ca5b

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= "*\\Windows\\CurrentVersion\\AppHost\\EnableWebContentEvaluation"  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_disable_web_evaluation_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_impair_defense_disable_web_evaluation_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 web content evaluation feature set to disable 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

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