MacOS List Firewall Rules

name: MacOS List Firewall Rules
id: f8db6e0b-55bb-40ca-bc85-2b3700adb0f8
version: 1
date: '2025-09-08'
author: Jamie Windley, Splunk
status: production
type: Anomaly
description: |
    This analytic detects attempts to enumerate or verify the configuration of the macOS application firewall.
    Specifically, it monitors executions of `defaults read /Library/Preferences/com.apple.alf` and `/usr/libexec/ApplicationFirewall/socketfilterfw --getglobalstate`.
    These commands provide insight into firewall status, allowed applications, and explicit authorization rules.
    While they are legitimate administrative operations, adversaries may leverage them to identify potential attack surfaces, determine whether the firewall is active, or enumerate allowed network flows.
    Monitoring for these commands, particularly when executed by non-administrative users or at unusual times, can provide early indication of reconnaissance activity on macOS endpoints
data_source:
    - Osquery Results
search: |
    | tstats `security_content_summariesonly`
      count
      values(Processes.parent_process) AS parent_process
      values(Processes.parent_process_exec) AS parent_process_exec
      values(Processes.parent_process_id) AS parent_process_id
      values(Processes.parent_process_name) AS parent_process_name
      values(Processes.parent_process_path) AS parent_process_path
      min(_time) as firstTime
      max(_time) as lastTime

    from datamodel=Endpoint.Processes where
    (
    Processes.process_name = "defaults"
    Processes.process = "* read *",
    Processes.process = "*/Library/Preferences/com.apple.alf*"
    )
    OR
    (
      Processes.process_name = "socketfilterfw"
      Processes.process = "*--getglobalstate*"
    )

    by Processes.action Processes.dest Processes.process Processes.process_hash
       Processes.process_id Processes.process_name Processes.process_path
       Processes.user Processes.vendor_product

    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `macos_list_firewall_rules_filter`
how_to_implement: |
    Collection of process execution events from macOS endpoints is required. This can be achieved using osquery's `es_process_events` table, EndpointSecurity framework integrations, or an EDR platform capable of recording process command lines. Ensure that captured events include at least the process path, full command line, user context, and timestamp.
known_false_positives: |
    These commands are frequently executed by system administrators or IT personnel during routine configuration checks, troubleshooting, or automated maintenance scripts. Security tools or monitoring agents may also query firewall status for inventory or compliance purposes. To reduce false positives, consider excluding events from known administrative accounts, trusted management systems, or scheduled maintenance jobs.
references:
    - https://www.manpagez.com/man/8/socketfilterfw/
    - https://ss64.com/mac/defaults.html
drilldown_searches:
    - name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search user = "$user$" AND dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") starthoursago=168  | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
rba:
    message: MacOS firewall rules listed via $process_name$ by $user$ on $dest$ using the command line $process$
    risk_objects:
        - field: dest
          type: system
          score: 20
        - field: user
          type: user
          score: 20
    threat_objects:
        - field: parent_process_name
          type: parent_process_name
        - field: process_name
          type: process_name
        - field: process
          type: command
tags:
    analytic_story:
        - Network Discovery
    asset_type: Endpoint
    mitre_attack_id:
        - T1016
    product:
        - Splunk Enterprise
        - Splunk Enterprise Security
        - Splunk Cloud
    security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/refs/heads/master/datasets/attack_techniques/T1016/atomic_red_team/macos_net_discovery/macos_list_firewall_rules.log
          sourcetype: osquery:results
          source: osquery