{"id":"cde0a575-7d3d-4a49-9817-b8004a7bf105","title":"Uncommon New Firewall Rule Added In Windows Firewall Exception List","description":"Detects when a rule has been added to the Windows Firewall exception list","author":"frack113","status":"test","level":"medium","date":"2022-02-19","modified":"2025-10-08","tags":["attack.defense-impairment","attack.t1686.003"],"technique_ids":["T1686.003"],"logsource":{"product":"windows","service":"firewall-as"},"falsepositives":[],"references":["https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-r2-and-2008/dd364427(v=ws.10)"],"source_path":"rules/windows/builtin/firewall_as/win_firewall_as_add_rule.yml","source_sha256":"2efd8b38742e3f3b8f033899a652e323b9963399f8a485d15eb4949a2d56dc04","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/windows/builtin/firewall_as/win_firewall_as_add_rule.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Uncommon New Firewall Rule Added In Windows Firewall Exception List\nid: cde0a575-7d3d-4a49-9817-b8004a7bf105\nstatus: test\ndescription: Detects when a rule has been added to the Windows Firewall exception list\nreferences:\n    - https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-r2-and-2008/dd364427(v=ws.10)\nauthor: frack113\ndate: 2022-02-19\nmodified: 2025-10-08\ntags:\n    - attack.defense-impairment\n    - attack.t1686.003\nlogsource:\n    product: windows\n    service: firewall-as\ndetection:\n    selection:\n        EventID:\n            - 2004 # A rule has been added to the Windows Defender Firewall exception list\n            - 2071 # A rule has been added to the Windows Defender Firewall exception list. (Windows 11)\n            - 2097\n    filter_main_block:\n        Action: 2 # Block\n    filter_main_generic:\n        ApplicationPath|startswith:\n            - 'C:\\Program Files (x86)\\'\n            - 'C:\\Program Files\\'\n            - 'C:\\Windows\\System32\\'\n            - 'C:\\Windows\\SysWOW64\\'\n            - 'C:\\Windows\\WinSxS\\'\n    filter_main_covered_paths:\n        # This filter is added to avoid duplicate alerting from 9e2575e7-2cb9-4da1-adc8-ed94221dca5e\n        ApplicationPath|contains:\n            - 'C:\\PerfLogs\\'\n            - 'C:\\Temp\\'\n            - 'C:\\Tmp\\'\n            - 'C:\\Users\\Public\\'\n            - 'C:\\Windows\\Tasks\\'\n            - 'C:\\Windows\\Temp\\'\n            - '\\AppData\\Local\\Temp\\'\n    filter_main_system_dllhost:\n        ApplicationPath: 'System'\n        ModifyingApplication: 'C:\\Windows\\System32\\dllhost.exe'\n    filter_main_tiworker:\n        ModifyingApplication|startswith: 'C:\\Windows\\WinSxS\\'\n        ModifyingApplication|endswith: '\\TiWorker.exe'\n    filter_main_null:\n        ApplicationPath: null\n    filter_optional_no_path:\n        # This filter filters a lot of FPs related to Windows Services\n        ModifyingApplication:\n            - 'C:\\Windows\\System32\\svchost.exe'\n            - 'C:\\Windows\\System32\\dllhost.exe'\n        ApplicationPath: ''\n    filter_optional_msmpeng:\n        - ModifyingApplication|startswith:\n              - 'C:\\ProgramData\\Microsoft\\Windows Defender\\Platform\\'\n              - 'C:\\Program Files\\Windows Defender\\'\n          ModifyingApplication|endswith: '\\MsMpEng.exe'\n        - ApplicationPath|startswith:\n              - 'C:\\ProgramData\\Microsoft\\Windows Defender\\Platform\\'\n              - 'C:\\Program Files\\Windows Defender\\'\n          ApplicationPath|endswith: '\\MsMpEng.exe'\n    condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*\nlevel: medium\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1686.003","id":"T1686.003","name":"Windows Host Firewall","page":"techniques/enterprise/T1686.003/"}],"data_path":"data/detection-rules/cde0a575-7d3d-4a49-9817-b8004a7bf105.json","kind":"sigma"}