Allow Network Discovery In Firewall

name: Allow Network Discovery In Firewall
id: ccd6a38c-d40b-11eb-85a5-acde48001122
version: 14
creation_date: '2021-06-23'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic detects a suspicious modification to the firewall to allow network discovery on a machine. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving the 'netsh' command to enable network discovery. This activity is significant because it is commonly used by ransomware, such as REvil and RedDot, to discover and compromise additional machines on the network. If confirmed malicious, this could lead to widespread file encryption across multiple hosts, significantly amplifying the impact of the ransomware attack.
data_source:
    - Sysmon EventID 1
    - Windows Event Log Security 4688
    - CrowdStrike ProcessRollup2
search: |-
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
      WHERE `process_netsh` Processes.process= "*firewall*" Processes.process= "*group=\"Network Discovery\"*"  Processes.process="*enable*" Processes.process="*Yes*"
      BY Processes.action Processes.dest Processes.original_file_name
         Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
         Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
         Processes.process Processes.process_exec Processes.process_guid
         Processes.process_hash Processes.process_id Processes.process_integrity_level
         Processes.process_name Processes.process_path Processes.user
         Processes.user_id Processes.vendor_product
    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `allow_network_discovery_in_firewall_filter`
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: network admin may modify this firewall feature that may cause this rule to be triggered.
references:
    - https://community.fortinet.com:443/t5/FortiEDR/How-FortiEDR-detects-and-blocks-Revil-Ransomware-aka-sodinokibi/ta-p/189638?externalID=FD52469
    - https://app.any.run/tasks/c0f98850-af65-4352-9746-fbebadee4f05/
finding:
    title: Suspicious modification to the firewall to allow network discovery detected on host - $dest$
    entity:
        field: user
        type: user
        score: 50
analytic_story:
    - BlackByte Ransomware
    - NjRAT
    - Revil Ransomware
    - Ransomware
    - Medusa Ransomware
    - Hellcat Ransomware
asset_type: Endpoint
mitre_attack_id:
    - T1686.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint