Potential DLL File Download Via PowerShell Invoke-WebRequest

SIGMA detection rule by Florian Roth (Nextron Systems), Hieu Tran · NOASSERTION

Detects potential DLL files being downloaded using the PowerShell Invoke-WebRequest or Invoke-RestMethod cmdlets.

title: Potential DLL File Download Via PowerShell Invoke-WebRequest
id: 0f0450f3-8b47-441e-a31b-15a91dc243e2
status: test
description: Detects potential DLL files being downloaded using the PowerShell Invoke-WebRequest or Invoke-RestMethod cmdlets.
references:
    - https://www.zscaler.com/blogs/security-research/onenote-growing-threat-malware-distribution
author: Florian Roth (Nextron Systems), Hieu Tran
date: 2023-03-13
modified: 2025-07-18
tags:
    - attack.command-and-control
    - attack.execution
    - attack.t1059.001
    - attack.t1105
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        CommandLine|contains:
            - 'Invoke-RestMethod '
            - 'Invoke-WebRequest '
            - 'IRM '
            - 'IWR '
        CommandLine|contains|all:
            - 'http'
            - 'OutFile'
            - '.dll'
    condition: selection
falsepositives:
    - Unknown
level: medium
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_powershell_download_dll/info.yml

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

d2a0cb28-ca68-4bcf-93f3-1dca432d3c9f

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

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[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

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