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excel_spawning_powershell.yml
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excel_spawning_powershell.yml
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name: Excel Spawning PowerShell
id: 42d40a22-9be3-11eb-8f08-acde48001122
version: 2
date: '2023-11-07'
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 EventID 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.parent_process_name
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