SigmaHQ/rules/windows/sysmon/sysmon_powershell_download.yml

title: PowerShell Download from URL
status: experimental
description: Detects a Powershell process that contains download commands in its command line string
author: Florian Roth
tags:
    - attack.t1086
    - attack.execution
logsource:
    product: windows
    service: sysmon
detection:
    selection:
        EventID: 1
        Image: '*\powershell.exe'
        CommandLine: 
            - '*new-object system.net.webclient).downloadstring(*'
            - '*new-object system.net.webclient).downloadfile(*'
            - '*new-object net.webclient).downloadstring(*' # Ex. https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1086/T1086.md#atomic-test-2---bloodhound
            - '*new-object net.webclient).downloadfile(*' # Ex. https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1086/T1086.md#atomic-test-3---obfuscation-tests

    condition: selection
fields:
    - CommandLine
    - ParentCommandLine
falsepositives:
    - unknown
level: medium