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Detection rules › Sigma

Filter Driver Unloaded Via Fltmc.EXE

Status
test
Severity
medium
Log source
category process_creation, product windows
Author
Nasreddine Bencherchali (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detect filter driver unloading activity via fltmc.exe

MITRE ATT&CK coverage

TacticTechniques
Stealth
Defense Impairment

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation

Rule body

title: Filter Driver Unloaded Via Fltmc.EXE
id: 4931188c-178e-4ee7-a348-39e8a7a56821
related:
    - id: 4d7cda18-1b12-4e52-b45c-d28653210df8 # Sysmon specific
      type: derived
status: test
description: Detect filter driver unloading activity via fltmc.exe
references:
    - https://www.darkoperator.com/blog/2018/10/5/operating-offensively-against-sysmon
    - https://www.cybereason.com/blog/threat-analysis-report-lockbit-2.0-all-paths-lead-to-ransom
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-02-13
modified: 2025-10-07
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: 'unload'
    filter_optional_avira:
        ParentImage|contains:
            - '\AppData\Local\Temp\'
            - ':\Windows\Temp\'
        ParentImage|endswith: '\endpoint-protection-installer-x64.tmp'
        CommandLine|endswith:
            - 'unload rtp_filesystem_filter'
            - 'unload rtp_filter'
    filter_optional_manageengine:
        ParentImage: 'C:\Program Files (x86)\ManageEngine\uems_agent\bin\dcfaservice64.exe'
        CommandLine|endswith: 'unload DFMFilter'
    condition: all of selection_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: condition

all of selection_* and not 1 of filter_optional_*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\fltMC.exe'
    - OriginalFileName: 'fltMC.exe'

Stage 2: selection_cli

selection_cli:
    CommandLine|contains: 'unload'

Stage 3: not filter_optional_*

filter_optional_avira:
    ParentImage|contains:
        - '\AppData\Local\Temp\'
        - ':\Windows\Temp\'
    ParentImage|endswith: '\endpoint-protection-installer-x64.tmp'
    CommandLine|endswith:
        - 'unload rtp_filesystem_filter'
        - 'unload rtp_filter'
filter_optional_manageengine:
    ParentImage: 'C:\Program Files (x86)\ManageEngine\uems_agent\bin\dcfaservice64.exe'
    CommandLine|endswith: 'unload DFMFilter'

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
CommandLineends_withunload rtp_filesystem_filterexcludes:CommandLine field:"CommandLine" value:"unload rtp_filesystem_filter"
CommandLineends_withunload rtp_filterexcludes:CommandLine field:"CommandLine" value:"unload rtp_filter"
ParentImagematch:\Windows\Temp\excludes:ParentImage field:"ParentImage" value:":\Windows\Temp\"
ParentImagematch\AppData\Local\Temp\excludes:ParentImage field:"ParentImage" value:"\AppData\Local\Temp\"
ParentImageends_with\endpoint-protection-installer-x64.tmpexcludes:ParentImage field:"ParentImage" value:"\endpoint-protection-installer-x64.tmp"
CommandLineends_withunload DFMFilterexcludes:CommandLine field:"CommandLine" value:"unload DFMFilter"
ParentImageeqC:\Program Files (x86)\ManageEngine\uems_agent\bin\dcfaservice64.exeexcludes:ParentImage field:"ParentImage" value:"C:\Program Files (x86)\ManageEngine\uems_agent\bin\dcfaservice64.exe"

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • unload corpus 5 (sigma 4, splunk 1)
field:"CommandLine" kind:match value:"unload"
Imageends_with
  • \fltMC.exe corpus 3 (sigma 3)
field:"Image" kind:ends_with value:"\fltMC.exe"
OriginalFileNameeq
  • fltMC.exe corpus 3 (sigma 2, elastic 1)
field:"OriginalFileName" kind:eq value:"fltMC.exe"