Windows File Association Modification via Ftype

SPLUNK detection rule by Raven Tait, Splunk · Apache-2.0

This analytic detects the use of the `ftype` command to modify Windows file associations. Attackers can abuse this functionality to change how specific file types are handled, potentially redirecting legitimate file execution to malicious payloads. If confirmed malicious, this behavior may enable persistence, execution of unauthorized code, or evasion of security controls.

name: Windows File Association Modification via Ftype
id: bab530d7-f3b4-428d-a3e6-30d7d0393fc8
version: 2
creation_date: '2021-09-02'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: Anomaly
description: |-
    This analytic detects the use of the `ftype` command to modify Windows file associations.
    Attackers can abuse this functionality to change how specific file types are handled, potentially redirecting legitimate file execution to malicious payloads.
    If confirmed malicious, this behavior may enable persistence, execution of unauthorized code, or evasion of security controls.
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

    Processes.process="*ftype*=*"

    by Processes.process Processes.vendor_product Processes.user_id
       Processes.process_hash Processes.parent_process_name
       Processes.parent_process_exec Processes.action Processes.dest
       Processes.process_current_directory Processes.process_path
       Processes.process_integrity_level Processes.original_file_name
       Processes.parent_process Processes.parent_process_path
       Processes.parent_process_guid Processes.parent_process_id
       Processes.process_guid Processes.process_id
       Processes.user Processes.process_name

    | `drop_dm_object_name(Processes)`
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_file_association_modification_via_ftype_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: Legitimate users or administrators may run the ftype command to check or modify file associations. Filter alerts if used within authorized maintenance activities.
drilldown_searches:
    - earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
      name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
    - 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"
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: File Association Modification via Ftype using the command $process$ activity observed on $dest$.
threat_objects:
    - field: parent_process_name
      type: parent_process_name
    - field: process
      type: process
    - field: process_name
      type: process_name
analytic_story:
    - Windows File Extension and Association Abuse
asset_type: Endpoint
mitre_attack_id:
    - T1059.003
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/attack_techniques/T1059.003/snapattack/snapattack.log
          source: XmlWinEventLog:Security
          sourcetype: XmlWinEventLog
      test_type: unit

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