Windows Office Product Dropped Uncommon File

name: Windows Office Product Dropped Uncommon File
id: 7ac0fced-9eae-4381-a748-90dcd1aa9393
version: 9
creation_date: '2021-09-14'
modification_date: '2026-05-13'
author: Teoderick Contreras, Michael Haag, Splunk, TheLawsOfChaos, Github
status: production
type: Anomaly
description: The following analytic detects Microsoft Office applications dropping or creating executables or scripts on a Windows OS. It leverages process creation and file system events from the Endpoint data model to identify Office applications like Word or Excel generating files with extensions such as ".exe", ".dll", or ".ps1". This behavior is significant as it is often associated with spear-phishing attacks where malicious files are dropped to compromise the host. If confirmed malicious, this activity could lead to code execution, privilege escalation, or persistent access, posing a severe threat to the environment.
data_source:
    - Sysmon EventID 1 AND Sysmon EventID 11
search: |-
    | tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes
      WHERE `process_office_products`
      BY _time span=1h 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)`
    | join process_guid, _time [
    | tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem
      WHERE Filesystem.file_name IN ("*.dll", "*.exe", "*.js", "*.pif", "*.ps1", "*.scr", "*.vbe", "*.vbs")
      BY _time span=1h Filesystem.dest
         Filesystem.file_create_time Filesystem.file_name Filesystem.process_guid
         Filesystem.file_path
    | `drop_dm_object_name(Filesystem)`
    | fields _time dest file_create_time file_name file_path process_name process_path process process_guid]
    | dedup file_create_time
    | table dest, process_name, process, file_create_time, file_name, file_path, process_guid
    | `windows_office_product_dropped_uncommon_file_filter`
how_to_implement: To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA. Tune and filter known instances where renamed rundll32.exe may be used.
known_false_positives: office macro for automation may do this behavior
references:
    - https://www.mandiant.com/resources/fin7-pursuing-an-enigmatic-and-evasive-global-criminal-operation
    - https://attack.mitre.org/groups/G0046/
    - https://www.joesandbox.com/analysis/702680/0/html
    - https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/trojanized-onenote-document-leads-to-formbook-malware/
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | 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: process $process_name$ drops a file $file_name$ in host $dest$
threat_objects:
    - field: process_name
      type: process_name
analytic_story:
    - CVE-2023-21716 Word RTF Heap Corruption
    - Warzone RAT
    - FIN7
    - Compromised Windows Host
    - AgentTesla
    - PlugX
asset_type: Endpoint
mitre_attack_id:
    - T1566.001
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/fin7/fin7_macro_js_1/sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit