Windows Registry: Disabling Antivirus Filter Driver on Dev Drive via FltmgrDevDriveAllowAntivirusFilter

Detects registry changes disabling antivirus minifilter inspection on a Dev Drive by setting the allow setting to 0x0.

FreeUnreviewedSigmahighv1

windows-registry-disabling-antivirus-filter-driver-on-dev-drive-via-fltmgrdevdri-31e124fb

title: "Windows Registry: Disabling Antivirus Filter Driver on Dev Drive via FltmgrDevDriveAllowAntivirusFilter"
id: e3b29890-fe38-4f19-b8b3-3a20b881b6ca
status: test
description: This rule flags a registry write that sets the Dev Drive antivirus filter allow setting to DWORD 0x00000000 under the FilterManager FltmgrDevDriveAllowAntivirusFilter path. Disabling this capability can impair security monitoring by preventing antivirus minifilters from inspecting a Dev Drive. It relies on Windows registry set telemetry capturing the TargetObject and the Details value being written.
references:
  - https://twitter.com/0gtweet/status/1720419490519752955
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_set/registry_set_devdrv_disallow_antivirus_filter.yml
author: "@kostastsale, Nasreddine Bencherchali (Nextron Systems), Huntrule Team"
date: 2023-11-05
modified: 2024-08-16
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  category: registry_set
  product: windows
detection:
  selection:
    TargetObject|endswith: \FilterManager\FltmgrDevDriveAllowAntivirusFilter
    Details: DWORD (0x00000000)
  condition: selection
falsepositives:
  - Unlikely
level: high
license: DRL-1.1
related:
  - id: 31e124fb-5dc4-42a0-83b3-44a69c77b271
    type: derived

What it detects

This rule flags a registry write that sets the Dev Drive antivirus filter allow setting to DWORD 0x00000000 under the FilterManager FltmgrDevDriveAllowAntivirusFilter path. Disabling this capability can impair security monitoring by preventing antivirus minifilters from inspecting a Dev Drive. It relies on Windows registry set telemetry capturing the TargetObject and the Details value being written.

Known false positives

Unlikely

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.