Windows Outlook Macro Created by Suspicious Process

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

The following analytic detects the creation of an Outlook Macro (VbaProject.OTM) by a suspicious process. This file is normally created when you create a macro from within Outlook. If this file is created by a process other than Outlook.exe it may be maliciously created. This detection leverages data from the Filesystem datamodel, specifically looking for the file creation event for VbaProject.OTM. This activity is significant as it is commonly associated with some malware infections, indicating potential malicious intent to harvest email information.

name: Windows Outlook Macro Created by Suspicious Process
id: 3ec347e3-a94a-4a8b-a918-8306ea403182
version: 4
creation_date: '2023-05-01'
modification_date: '2026-05-13'
author: Raven Tait, Splunk
status: production
type: TTP
description: The following analytic detects the creation of an Outlook Macro (VbaProject.OTM) by a suspicious process. This file is normally created when you create a macro from within Outlook. If this file is created by a process other than Outlook.exe it may be maliciously created. This detection leverages data from the Filesystem datamodel, specifically looking for the file creation event for VbaProject.OTM. This activity is significant as it is commonly associated with some malware infections, indicating potential malicious intent to harvest email information.
data_source:
    - Sysmon EventID 11
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime values(Filesystem.file_create_time) as file_create_time from datamodel=Endpoint.Filesystem where Filesystem.file_path="*Appdata\\Roaming\\Microsoft\\Outlook\\VbaProject.OTM" by Filesystem.action Filesystem.dest Filesystem.file_access_time Filesystem.file_create_time Filesystem.file_hash Filesystem.file_modify_time Filesystem.file_name Filesystem.file_path Filesystem.file_acl Filesystem.file_size Filesystem.process_guid Filesystem.process_id Filesystem.user Filesystem.vendor_product | `drop_dm_object_name(Filesystem)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_outlook_macro_created_by_suspicious_process_filter`'
how_to_implement: You must be ingesting data that records file-system activity from your hosts to populate the Endpoint file-system data-model node. If you are using Sysmon, you will need a Splunk Universal Forwarder on each endpoint from which you want to collect data.
known_false_positives: Because this file are always created by Outlook in normal operations, you should investigate all results.
references:
    - https://lab52.io/blog/analyzing-notdoor-inside-apt28s-expanding-arsenal/
    - https://hackread.com/russian-apt28-notdoor-backdoor-microsoft-outlook/
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: Suspicious Outlook macro $file_name$ created on $dest$
    entity:
        field: user
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: Suspicious Outlook macro $file_name$ created on $dest$
threat_objects:
    - field: file_name
      type: file_name
analytic_story:
    - NotDoor Malware
asset_type: Endpoint
mitre_attack_id:
    - T1137
    - T1059.005
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/notdoor/outlook_macro/windows-sysmon.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

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