Windows: Sysmon filter driver unloaded using fltMC.exe

Identifies fltMC.exe commands attempting to unload the Sysmon filter driver via “unload sysmon”.

FreeReviewedSigma · High · v2

Product: windows
Category: process_creation
Author: Kirill Kiryanov, oscd.community (SigmaHQ), DRL 1.1
Published: 2019-10-23
Updated: 2026-07-31

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1070Indicator Removal
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags process executions where fltMC.exe is used with command-line arguments that include both 'unload' and 'sysmon', indicating an attempt to unload the Sysmon filter driver. Attackers may use driver unloading to reduce visibility or impair defensive monitoring. It relies on Windows process creation telemetry, matching the process image/original filename and the contents of the command line.

Reporting behind it

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Windows: Sysmon filter driver unloaded using fltMC.exe

Pivot detection · T1070 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

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

windows-sysmon-filter-driver-unloaded-using-fltmc-exe-4d7cda18

title: "Windows: Sysmon filter driver unloaded using fltMC.exe"
id: 1567156c-ed87-4e84-9873-7e2df3e6bece
related:
  - id: 4931188c-178e-4ee7-a348-39e8a7a56821
    type: similar
  - id: 4d7cda18-1b12-4e52-b45c-d28653210df8
    type: derived
status: test
description: This rule flags process executions where fltMC.exe is used with command-line arguments that include both 'unload' and 'sysmon', indicating an attempt to unload the Sysmon filter driver. Attackers may use driver unloading to reduce visibility or impair defensive monitoring. It relies on Windows process creation telemetry, matching the process image/original filename and the contents of the command line.
references:
  - https://www.darkoperator.com/blog/2018/10/5/operating-offensively-against-sysmon
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_fltmc_unload_driver_sysmon.yml
author: Kirill Kiryanov, oscd.community, Huntrule Team
date: 2019-10-23
modified: 2023-02-13
tags:
  - attack.stealth
  - attack.defense-impairment
  - attack.t1070
  - attack.t1685
  - attack.t1685.001
logsource:
  product: windows
  category: process_creation
detection:
  selection_img:
    - Image|endswith: \fltMC.exe
    - OriginalFileName: fltMC.exe
  selection_cli:
    CommandLine|contains|all:
      - unload
      - sysmon
  condition: all of selection_*
falsepositives:
  - Unlikely
level: high
license: DRL-1.1

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