Unusual New Firewall Rule Added In Windows Firewall Exception List (via firewall-as)

title: Unusual New Firewall Rule Added In Windows Firewall Exception List (via firewall-as)
id: 52259908-6c68-55ad-bdf7-e199e3fbdebe
status: stable
description: This rule detects when a rule has been added to the Windows Firewall exception list
references:
    - https://attack.mitre.org/techniques/T1686/003/
    - https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-r2-and-2008/dd364427(v=ws.10)
author: Huntrule Team
date: 2026-02-18
tags:
    - attack.defense-impairment
    - attack.t1686.003
logsource:
    product: windows
    service: firewall-as
detection:
    selection:
        EventID:
            - 2004
            - 2071
            - 2097
    filter_main_block:
        Action: 2
    filter_main_generic:
        ApplicationPath|startswith:
            - 'C:\Program Files (x86)\'
            - 'C:\Program Files\'
            - 'C:\Windows\System32\'
            - 'C:\Windows\SysWOW64\'
            - 'C:\Windows\WinSxS\'
    filter_main_covered_paths:
        ApplicationPath|contains:
            - 'C:\PerfLogs\'
            - 'C:\Temp\'
            - 'C:\Tmp\'
            - 'C:\Users\Public\'
            - 'C:\Windows\Tasks\'
            - 'C:\Windows\Temp\'
            - '\AppData\Local\Temp\'
    filter_main_system_dllhost:
        ApplicationPath: 'System'
        ModifyingApplication: 'C:\Windows\System32\dllhost.exe'
    filter_main_tiworker:
        ModifyingApplication|startswith: 'C:\Windows\WinSxS\'
        ModifyingApplication|endswith: '\TiWorker.exe'
    filter_main_null:
        ApplicationPath:
    filter_optional_no_path:
        ModifyingApplication:
            - 'C:\Windows\System32\svchost.exe'
            - 'C:\Windows\System32\dllhost.exe'
        ApplicationPath: ''
    filter_optional_msmpeng:
        - ModifyingApplication|startswith:
              - 'C:\ProgramData\Microsoft\Windows Defender\Platform\'
              - 'C:\Program Files\Windows Defender\'
          ModifyingApplication|endswith: '\MsMpEng.exe'
        - ApplicationPath|startswith:
              - 'C:\ProgramData\Microsoft\Windows Defender\Platform\'
              - 'C:\Program Files\Windows Defender\'
          ApplicationPath|endswith: '\MsMpEng.exe'
    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium