Windows Get-Variable.EXE Execution from WindowsApps Folder

Name:Windows Get-Variable.EXE Execution from WindowsApps Folder
id:7edb95b6-bccf-4d8c-8ada-d1c5520cf0ed
version:2
date:None
author:Raven Tait, Splunk
status:production
type:Anomaly
Description:An attacker can obtain persistence by hijacking the PowerShell cmdlet 'Get-Variable' by placing Get-Variable.exe in the WindowsApps folder, which is part of the PowerShell path. Whenever a PowerShell window is opened via a scheduled task, the malicious Get-Variable.exe will be run. This activity was first associated with the Colibri malware.
Data_source:

• -Sysmon EventID 1
• -Windows Event Log Security 4688
• -CrowdStrike ProcessRollup2

search:| tstats `security_content_summariesonly`
count min(_time) as firstTime
max(_time) as lastTime

from datamodel=Endpoint.Processes where

Processes.process_path="*\\AppData\\Local\\Microsoft\\WindowsApps\\Get-Variable.exe"

by Processes.process Processes.vendor_product Processes.user_id Processes.process_hash
Processes.parent_process_name Processes.parent_process_exec Processes.action
Processes.dest Processes.process_current_directory Processes.process_path
Processes.process_integrity_level Processes.original_file_name Processes.parent_process
Processes.parent_process_path Processes.parent_process_guid Processes.parent_process_id
Processes.process_guid Processes.process_id Processes.user Processes.process_name

| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_get_variable_exe_execution_from_windowsapps_folder_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:Some legitimate administrative tools may use custom executables in the WindowsApps folder for persistence or automation. Verify the executable's origin before flagging to avoid false positives.
References:
  -https://thehackernews.com/2022/04/researchers-uncover-how-colibri-malware.html
drilldown_searches:
 earliest_offset:'$info_min_time$'
 latest_offset:'$info_max_time$'
 name:'View the detection results for - "$user$" and "$dest$"'
 search:'%original_detection_search% | search user = "$user$" dest = "$dest$"'
 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'
analytic_story:['Windows Persistence Techniques']

asset_type:Endpoint

mitre_attack_id:['T1574.008']

product:['Splunk Enterprise', 'Splunk Enterprise Security', 'Splunk Cloud']

category:endpoint

security_domain:endpoint

tags:

tests:
 name:'True Positive Test'
 attack_data:
  data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1574.008/snapattack/snapattack.log
  source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
  sourcetype: XmlWinEventLog
 test_type:'unit'
manual_test:None