Suspicious PowerShell Download - Powershell Script (via ps_script)

title: Suspicious PowerShell Download - Powershell Script (via ps_script)
id: 2cb0bed5-d169-5ad7-85c8-4488fdc27233
status: stable
description: This rule detects anomalous PowerShell download command
references:
    - https://attack.mitre.org/techniques/T1059/001/
    - https://learn.microsoft.com/en-us/dotnet/api/system.net.webclient.downloadstring?view=net-8.0
    - https://learn.microsoft.com/en-us/dotnet/api/system.net.webclient.downloadfile?view=net-8.0
author: Huntrule Team
date: 2026-02-21
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    webclient:
        ScriptBlockText|contains: 'System.Net.WebClient'
    download:
        ScriptBlockText|contains:
            - '.DownloadFile('
            - '.DownloadFileAsync('
            - '.DownloadString('
            - '.DownloadStringAsync('
    condition: webclient and download
falsepositives:
    - Unknown
level: medium