Windows Process Executed From Removable Media

name: Windows Process Executed From Removable Media
id: b483804a-4cc0-49a4-9f00-ac29ba844d08
version: 10
creation_date: '2025-01-17'
modification_date: '2026-05-13'
author: Steven Dick
status: production
type: Anomaly
description: This analytic is used to identify when a removable media device is attached to a machine and then a process is executed from the same drive letter assigned to the removable media device. Adversaries and Insider Threats may use removable media devices for several malicious activities, including initial access, execution, and exfiltration.
data_source:
    - Sysmon EventID 1 AND Sysmon EventID 13
search: |-
    | tstats `security_content_summariesonly` count values(Processes.process) as process min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Processes
      WHERE Processes.process_current_directory=*
        AND
        NOT Processes.process_current_directory IN ("C:\\*","*\\sysvol\\*")
      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 Processes.process_current_directory
    | `drop_dm_object_name(Processes)`
    | rex field=process_current_directory "^(?<object_handle>[^\\\]+\\\)"
    | where isnotnull(object_handle)
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | join dest,object_handle
    [
    | tstats `security_content_summariesonly` count values(Registry.action) as action values(Registry.process_guid) as process_guid values(Registry.process_id) as process_id values(Registry.registry_hive) as registry_hive values(Registry.registry_key_name) as registry_key_name values(Registry.registry_value_name) as registry_value_name values(Registry.registry_value_type) as registry_value_type values(Registry.status) as status values(Registry.user) as user values(Registry.vendor_product) as vendor_product FROM datamodel=Endpoint.Registry
      WHERE Registry.registry_value_data="*:\\*"
        AND
        Registry.registry_path="*USBSTOR*"
        AND
        Registry.registry_path IN ("HKLM\\SOFTWARE\\Microsoft\\Windows Portable Devices\\Devices\\*","HKLM\\System\\CurrentControlSet\\Enum\\SWD\\WPDBUSENUM\\*")
      BY Registry.dest,Registry.registry_value_data, Registry.registry_path
    | `drop_dm_object_name(Registry)`
    | eval object_handle = registry_value_data, object_name = replace(mvindex(split(mvindex(split(registry_path, "??"),1),"&"),2),"PROD_","")
        ]
    | `windows_process_executed_from_removable_media_filter`
how_to_implement: To successfully implement this search, you must ingest endpoint logging that tracks changes to the HKLM\SOFTWARE\Microsoft\Windows Portable Devices\Devices\ or HKLM\System\CurrentControlSet\Enum\SWD\WPDBUSENUM\ registry keys as well as Process Execution commands. Ensure that the field from the event logs is being mapped to the proper fields in the Endpoint.Registry data model. This analytic joins the Process and Registry datamodels together based on the drive letter extract to the "object_handle" field from both datasets.
known_false_positives: Legitimate USB activity will also be detected. Please verify and investigate as appropriate.
references:
    - https://attack.mitre.org/techniques/T1200/
    - https://www.cisa.gov/news-events/news/using-caution-usb-drives
    - https://www.bleepingcomputer.com/news/security/fbi-hackers-use-badusb-to-target-defense-firms-with-ransomware/
intermediate_findings:
    entities:
        - field: user
          type: user
          score: 20
          message: The process [$process_name$] was launched using files on a removable storage device named [$object_name$] by [$user$] on $dest$
        - field: dest
          type: system
          score: 20
          message: The process [$process_name$] was launched using files on a removable storage device named [$object_name$] by [$user$] on $dest$
threat_objects:
    - field: object_handle
      type: registry_value_text
    - field: object_name
      type: registry_value_name
    - field: process_name
      type: process_name
analytic_story:
    - Data Protection
    - APT37 Rustonotto and FadeStealer
asset_type: Endpoint
mitre_attack_id:
    - T1200
    - T1025
    - T1091
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint