Uncommon New Firewall Rule Added In Windows Firewall Exception List

Status: test
Severity: medium
Log source: product windows, service firewall-as
Author: frack113
Source: github.com/SigmaHQ/sigma

Detects when a rule has been added to the Windows Firewall exception list

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1686.003` Disable or Modify System Firewall: Windows Host Firewall

Event coverage

Provider	Event
Windows-Firewall-With-Advanced-Security	Event ID 2004
Windows-Firewall-With-Advanced-Security	Event ID 2071
Windows-Firewall-With-Advanced-Security	Event ID 2097

Rule body yaml

title: Uncommon New Firewall Rule Added In Windows Firewall Exception List
id: cde0a575-7d3d-4a49-9817-b8004a7bf105
status: test
description: Detects when a rule has been added to the Windows Firewall exception list
references:
    - https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-r2-and-2008/dd364427(v=ws.10)
author: frack113
date: 2022-02-19
modified: 2025-10-08
tags:
    - attack.defense-impairment
    - attack.t1686.003
logsource:
    product: windows
    service: firewall-as
detection:
    selection:
        EventID:
            - 2004 # A rule has been added to the Windows Defender Firewall exception list
            - 2071 # A rule has been added to the Windows Defender Firewall exception list. (Windows 11)
            - 2097
    filter_main_block:
        Action: 2 # Block
    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:
        # This filter is added to avoid duplicate alerting from 9e2575e7-2cb9-4da1-adc8-ed94221dca5e
        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: null
    filter_optional_no_path:
        # This filter filters a lot of FPs related to Windows Services
        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_*
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_main_* and not 1 of filter_optional_*

Stage 1: `selection`

selection:
    EventID:
        - 2004
        - 2071
        - 2097

Stage 2: `not filter_main_*`

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: null

Stage 3: `not filter_optional_*`

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'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`ApplicationPath`	eq	`System`
`ModifyingApplication`	eq	`C:\Windows\System32\dllhost.exe`
`ModifyingApplication`	ends_with	`\TiWorker.exe`
`ModifyingApplication`	starts_with	`C:\Windows\WinSxS\`
`Action`	eq	`2`
`ApplicationPath`	is_null	(no value, null check)
`ApplicationPath`	match	`C:\PerfLogs\`
`ApplicationPath`	match	`C:\Temp\`
`ApplicationPath`	match	`C:\Tmp\`
`ApplicationPath`	match	`C:\Users\Public\`
`ApplicationPath`	match	`C:\Windows\Tasks\`
`ApplicationPath`	match	`C:\Windows\Temp\`
`ApplicationPath`	match	`\AppData\Local\Temp\`
`ApplicationPath`	starts_with	`C:\Program Files (x86)\`
`ApplicationPath`	starts_with	`C:\Program Files\`
`ApplicationPath`	starts_with	`C:\Windows\SysWOW64\`
`ApplicationPath`	starts_with	`C:\Windows\System32\`
`ApplicationPath`	starts_with	`C:\Windows\WinSxS\`
`ApplicationPath`	starts_with	`C:\Program Files\Windows Defender\`
`ApplicationPath`	starts_with	`C:\ProgramData\Microsoft\Windows Defender\Platform\`
`ApplicationPath`	ends_with	`\MsMpEng.exe`
`ModifyingApplication`	eq	`C:\Windows\System32\dllhost.exe`
`ModifyingApplication`	eq	`C:\Windows\System32\svchost.exe`
`ModifyingApplication`	starts_with	`C:\Program Files\Windows Defender\`
`ModifyingApplication`	starts_with	`C:\ProgramData\Microsoft\Windows Defender\Platform\`
`ModifyingApplication`	ends_with	`\MsMpEng.exe`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Uncommon New Firewall Rule Added In Windows Firewall Exception List

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_*`

Stage 3: `not filter_optional_*`

Exclusions

Keyboard shortcuts

Search operators

Uncommon New Firewall Rule Added In Windows Firewall Exception List

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter_main_*

Stage 3: not filter_optional_*

Exclusions

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter_main_*`

Stage 3: `not filter_optional_*`