Suspicious Invoke-WebRequest Execution

SIGMA detection rule by Nasreddine Bencherchali (Nextron Systems) · NOASSERTION

Detects a suspicious call to Invoke-WebRequest cmdlet where the and output is located in a suspicious location

title: Suspicious Invoke-WebRequest Execution
id: 5e3cc4d8-3e68-43db-8656-eaaeefdec9cc
related:
    - id: e218595b-bbe7-4ee5-8a96-f32a24ad3468
      type: derived
status: test
description: Detects a suspicious call to Invoke-WebRequest cmdlet where the and output is located in a suspicious location
references:
    - https://www.sentinelone.com/blog/living-off-windows-defender-lockbit-ransomware-sideloads-cobalt-strike-through-microsoft-security-tool/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-08-02
modified: 2025-07-18
tags:
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\powershell_ise.exe'
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'powershell_ise.EXE'
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_commands:
        CommandLine|contains:
            # These are all aliases of Invoke-WebRequest
            - 'curl '
            - 'Invoke-WebRequest'
            - 'iwr '
            - 'wget '
    selection_flags:
        CommandLine|contains:
            - ' -ur'
            - ' -o'
    selection_susp_locations:
        CommandLine|contains:
            - '\AppData\'
            - '\Desktop\'
            - '\Temp\'
            - '\Users\Public\'
            - '%AppData%'
            - '%Public%'
            - '%Temp%'
            - '%tmp%'
            - ':\Windows\'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_powershell_invoke_webrequest_download/info.yml

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6e84aae2-e8a4-4040-927b-7f41ceda2e1a

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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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Format & documentation suggestions

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