title: HackTool - EDRSilencer Execution - Filter Added
id: 98054878-5eab-434c-85d4-72d4e5a3361b
status: test
description: |
    Detects execution of EDRSilencer, a tool that abuses the Windows Filtering Platform (WFP) to block the outbound traffic of running EDR agents based on specific hardcoded filter names.
references:
    - https://github.com/netero1010/EDRSilencer
author: Thodoris Polyzos (@SmoothDeploy)
date: 2024-01-29
modified: 2024-01-30
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    product: windows
    service: security
    definition: 'Requirements: Audit Filtering Platform Policy Change needs to be enabled'
detection:
    selection:
        EventID:
            - 5441
            - 5447
        FilterName|contains: 'Custom Outbound Filter'
    condition: selection
falsepositives:
    - Unknown
level: high

title: Antivirus Filter Driver Disallowed On Dev Drive - Registry
id: 31e124fb-5dc4-42a0-83b3-44a69c77b271
status: test
description: |
    Detects activity that indicates a user disabling the ability for Antivirus mini filter to inspect a "Dev Drive".
references:
    - https://twitter.com/0gtweet/status/1720419490519752955
author: '@kostastsale, Nasreddine Bencherchali (Nextron Systems)'
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

title: Dropping Of Password Filter DLL
id: b7966f4a-b333-455b-8370-8ca53c229762
status: test
description: Detects dropping of dll files in system32 that may be used to retrieve user credentials from LSASS
references:
    - https://pentestlab.blog/2020/02/10/credential-access-password-filter-dll/
    - https://github.com/3gstudent/PasswordFilter/tree/master/PasswordFilter
author: Sreeman
date: 2020-10-29
modified: 2022-10-09
tags:
    - attack.persistence
    - attack.credential-access
    - attack.defense-impairment
    - attack.t1556.002
logsource:
    category: process_creation
    product: windows
detection:
    selection_cmdline:
        CommandLine|contains|all:
            - 'HKLM\SYSTEM\CurrentControlSet\Control\Lsa'
            - 'scecli\0*'
            - 'reg add'
    condition: selection_cmdline
falsepositives:
    - Unknown
level: medium

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

title: WFP Filter Added via Registry
id: 1f1d8209-636e-4c6c-a137-781cca8b82f9
status: experimental
description: |
    Detects registry modifications that add Windows Filtering Platform (WFP) filters, which may be used to block security tools and EDR agents from reporting events.
references:
    - https://github.com/netero1010/EDRSilencer/blob/0e73a7037ec65c52894d8208e6f605a7da0a34a6/EDRSilencer.c
    - https://www.huntress.com/blog/silencing-the-edr-silencers
    - https://www.trendmicro.com/en_us/research/24/j/edrsilencer-disrupting-endpoint-security-solutions.html
author: Frack113
date: 2025-10-23
tags:
    - attack.execution
    - attack.defense-impairment
    - attack.t1685
    - attack.t1569.002
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains: '\BFE\Parameters\Policy\Persistent\Filter\'
    filter_main_svchost:
        Image:
            - 'C:\Windows\System32\svchost.exe'
            - 'C:\Windows\SysWOW64\svchost.exe'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium