splunk-security_content/removed/detections/any_powershell_downloadstring.yml

name: Any Powershell DownloadString
id: 4d015ef2-7adf-11eb-95da-acde48001122
version: 14
date: '2025-07-29'
author: Michael Haag, Splunk
status: removed
type: TTP
description: The following analytic detects the use of PowerShell's `DownloadString`
  method to download files. It leverages data from Endpoint Detection and Response
  (EDR) agents, focusing on process execution logs that include command-line details.
  This activity is significant because `DownloadString` is commonly used in malicious
  PowerShell scripts to fetch and execute remote code. If confirmed malicious, this
  behavior could allow an attacker to download and run arbitrary code, potentially
  leading to unauthorized access, data exfiltration, or further compromise of the
  affected system.
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 `process_powershell` Processes.process=*.DownloadString*
  by 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)` | `security_content_ctime(firstTime)`| `security_content_ctime(lastTime)`|
  `any_powershell_downloadstring_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 may be present and filtering will need to occur
  by parent process or command line argument. It may be required to modify this query
  to an EDR product for more granular coverage.
references:
- https://docs.microsoft.com/en-us/dotnet/api/system.net.webclient.downloadstring?view=net-5.0
- https://blog.malwarebytes.com/malwarebytes-news/2021/02/lazyscripter-from-empire-to-double-rat/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1059.001/T1059.001.md
- https://thedfirreport.com/2023/05/22/icedid-macro-ends-in-nokoyawa-ransomware/
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 ("$user$",
    "$dest$") starthoursago=168  | 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: $info_min_time$
  latest_offset: $info_max_time$
rba:
  message: An instance of $parent_process_name$ spawning $process_name$ was identified
    on endpoint $dest$ by user $user$. This behavior identifies the use of DownloadString
    within PowerShell.
  risk_objects:
  - field: user
    type: user
    score: 56
  - field: dest
    type: system
    score: 56
  threat_objects:
  - field: parent_process_name
    type: parent_process_name
  - field: process_name
    type: process_name
tags:
  analytic_story:
  - Winter Vivern
  - Phemedrone Stealer
  - Malicious PowerShell
  - Data Destruction
  - SysAid On-Prem Software CVE-2023-47246 Vulnerability
  - PHP-CGI RCE Attack on Japanese Organizations
  - Hermetic Wiper
  - IcedID
  - Ingress Tool Transfer
  - HAFNIUM Group
  - XWorm
  - Scattered Spider
  asset_type: Endpoint
  mitre_attack_id:
  - T1059.001
  - T1105
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1059.001/atomic_red_team/windows-sysmon.log
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
    sourcetype: XmlWinEventLog