Potential Persistence Via Powershell Search Order Hijacking - Task

SIGMA detection rule by pH-T (Nextron Systems), Florian Roth (Nextron Systems) · NOASSERTION

Detects suspicious powershell execution via a schedule task where the command ends with an suspicious flags to hide the powershell instance instead of executeing scripts or commands. This could be a sign of persistence via PowerShell "Get-Variable" technique as seen being used in Colibri Loader

title: Potential Persistence Via Powershell Search Order Hijacking - Task
id: b66474aa-bd92-4333-a16c-298155b120df
related:
    - id: 6e8811ee-90ba-441e-8486-5653e68b2299
      type: similar
status: test
description: Detects suspicious powershell execution via a schedule task where the command ends with an suspicious flags to hide the powershell instance instead of executeing scripts or commands. This could be a sign of persistence via PowerShell "Get-Variable" technique as seen being used in Colibri Loader
references:
    - https://blog.malwarebytes.com/threat-intelligence/2022/04/colibri-loader-combines-task-scheduler-and-powershell-in-clever-persistence-technique/
author: pH-T (Nextron Systems), Florian Roth (Nextron Systems)
date: 2022-04-08
modified: 2023-02-03
tags:
    - attack.privilege-escalation
    - attack.execution
    - attack.persistence
    - attack.t1053.005
    - attack.t1059.001
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        ParentImage: 'C:\WINDOWS\System32\svchost.exe'
        ParentCommandLine|contains|all:
            - '-k netsvcs'
            - '-s Schedule'
        CommandLine|endswith:
            - ' -windowstyle hidden'
            - ' -w hidden'
            - ' -ep bypass'
            - ' -noni'
    condition: selection
falsepositives:
    - Unknown
level: high

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

f38967f6-6ebb-4d30-a830-32b16b587194

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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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