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Description

The following analytic detects modifications to the Windows registry that disable Windows Defender Application Guard auditing. It leverages data from the Endpoint.Registry data model, focusing on specific registry paths and values. This activity is significant because disabling auditing can hinder security monitoring and threat detection within the isolated environment, making it easier for malicious activities to go unnoticed. If confirmed malicious, this action could allow attackers to bypass Windows Defender protections, potentially leading to unauthorized access, data exfiltration, or further system compromise.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-05-28
  • Author: Teoderick Contreras, Splunk
  • ID: 8b700d7e-54ad-4d7d-81cc-1456c4703306

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_path= "*\\Policies\\Microsoft\\AppHVSI\\AuditApplicationGuard" 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_disable_win_defender_app_guard_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_impair_defense_disable_win_defender_app_guard_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 AuditApplicationGuard 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

source | version: 2