Allow File And Printing Sharing In Firewall

SPLUNK detection rule by Teoderick Contreras, Splunk · Apache-2.0

The following analytic detects the modification of firewall settings to allow file and printer sharing. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving 'netsh' commands that enable file and printer sharing. This activity is significant because it can indicate an attempt by ransomware to discover and encrypt files on additional machines connected to the compromised host. If confirmed malicious, this could lead to widespread file encryption across the network, significantly increasing the impact of a ransomware attack.

name: Allow File And Printing Sharing In Firewall
id: ce27646e-d411-11eb-8a00-acde48001122
version: 15
creation_date: '2021-06-23'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic detects the modification of firewall settings to allow file and printer sharing. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving 'netsh' commands that enable file and printer sharing. This activity is significant because it can indicate an attempt by ransomware to discover and encrypt files on additional machines connected to the compromised host. If confirmed malicious, this could lead to widespread file encryption across the network, significantly increasing the impact of a 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=\"File and Printer Sharing\"*"
    Processes.process="*enable=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_file_and_printing_sharing_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/
drilldown_searches:
    - name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" 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 ("$user$", "$dest$") | 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: 7d
      latest_offset: "0"
finding:
    title: A suspicious modification of firewall to allow file and printer sharing detected on host - $dest$
    entity:
        field: user
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: A suspicious modification of firewall to allow file and printer sharing detected on host - $dest$
analytic_story:
    - Ransomware
    - BlackByte Ransomware
    - Hellcat Ransomware
asset_type: Endpoint
mitre_attack_id:
    - T1686.001
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/ransomware_ttp/data2/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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