splunk-security_content/removed/detections/any_powershell_downloadstring.yml

name: Any Powershell DownloadString
id: 4d015ef2-7adf-11eb-95da-acde48001122
version: 14
creation_date: '2021-03-01'
modification_date: '2026-05-13'
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
deprecation_info:
    reason: Detection has been replaced by a new detection with a better logic and grouping in order to ease its management.
    removed_in_version: 5.12.0
    replacement_content:
        - Windows File Download Via PowerShell