name: Excel Spawning PowerShell
id: 42d40a22-9be3-11eb-8f08-acde48001122
version: 1
date: '2021-04-12'
author: Michael Haag, Splunk
status: production
type: TTP
description: The following detection identifies Microsoft Excel spawning PowerShell.
  Typically, this is not common behavior and not default with Excel.exe. Excel.exe
  will generally be found in the following path `C:\Program Files\Microsoft Office\root\Office16`
  (version will vary). PowerShell spawning from Excel.exe is common for a spearphishing
  attachment and is actively used. Albeit, the command executed will most likely be
  encoded and captured via another detection. During triage, review parallel processes
  and identify any files that may have been written.
data_source:
- Sysmon Event ID 1
search: '| tstats `security_content_summariesonly` count values(Processes.process)
  min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes
  where Processes.parent_process_name="excel.exe" `process_powershell` by Processes.parent_process
  Processes.process_name Processes.user Processes.dest Processes.original_file_name
  | `drop_dm_object_name("Processes")` | `security_content_ctime(firstTime)`|`security_content_ctime(lastTime)`
  | `excel_spawning_powershell_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: False positives should be limited, but if any are present,
  filter as needed.
references:
- https://redcanary.com/threat-detection-report/techniques/powershell/
- https://attack.mitre.org/techniques/T1566/001/
tags:
  analytic_story:
  - Spearphishing Attachments
  asset_type: Endpoint
  confidence: 100
  impact: 80
  message: An instance of $parent_process_name$ spawning $process_name$ was identified
    on endpoint $dest$ by user $user$, indicating potential suspicious macro execution.
  mitre_attack_id:
  - T1003.002
  - T1003
  observable:
  - name: user
    type: User
    role:
    - Victim
  - name: dest
    type: Hostname
    role:
    - Victim
  - name: parent_process_name
    type: Process
    role:
    - Parent Process
  - name: process_name
    type: Process
    role:
    - Child Process
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - Processes.dest
  - Processes.user
  - Processes.parent_process_name
  - Processes.parent_process
  - Processes.original_file_name
  - Processes.process_name
  - Processes.process
  - Processes.process_id
  - Processes.parent_process_path
  - Processes.process_path
  - Processes.parent_process_id
  risk_score: 80
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1566.001/macro/windows-sysmon.log
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
    sourcetype: xmlwineventlog