Scheduled Task Executing Encoded Payload from Registry — Sigma Rule

Rule metadata and linked tags

Author: pH-T (Nextron Systems), @Kostastsale, TheDFIRReport, X__Junior (Nextron Systems), Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2022-02-12 / 2023-02-04.

{
  "product": "windows",
  "category": "process_creation"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 5ca6c1b9d45aa4075a15f5236649107256a9098ce0a154539bbb036e62fab770

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Scheduled Task Executing Encoded Payload from Registry
id: c4eeeeae-89f4-43a7-8b48-8d1bdfa66c78
status: test
description: Detects the creation of a schtask that potentially executes a base64 encoded payload stored in the Windows Registry using PowerShell.
references:
    - https://thedfirreport.com/2022/02/21/qbot-and-zerologon-lead-to-full-domain-compromise/
author: pH-T (Nextron Systems), @Kostastsale, TheDFIRReport, X__Junior (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2022-02-12
modified: 2023-02-04
tags:
    - attack.privilege-escalation
    - attack.execution
    - attack.persistence
    - attack.t1053.005
    - attack.t1059.001
logsource:
    product: windows
    category: process_creation
detection:
    selection_img:
        # schtasks.exe /Create /F /TN "{97F2F70B-10D1-4447-A2F3-9B070C86E261}" /TR "cmd /c start /min \"\" powershell.exe -Command IEX([System.Text.Encoding]::ASCII.GetString([System.Convert]::FromBase64String((Get-ItemProperty -Path HKCU:\SOFTWARE\Pvoeooxf).yzbbvhhdypa))) " /SC MINUTE /MO 30
        - Image|endswith: '\schtasks.exe'
        - OriginalFileName: 'schtasks.exe'
    selection_cli_create:
        CommandLine|contains: '/Create'
    selection_cli_encoding:
        CommandLine|contains:
            - 'FromBase64String'
            - 'encodedcommand'
    selection_cli_get:
        CommandLine|contains:
            - 'Get-ItemProperty'
            - ' gp ' # Alias
    selection_cli_hive:
        CommandLine|contains:
            - 'HKCU:'
            - 'HKLM:'
            - 'registry::'
            - 'HKEY_'
    condition: all of selection_*
falsepositives:
    - Unlikely
level: high

Original YAML and metadata in JSON

False positives

• Unlikely

Source references

• https://thedfirreport.com/2022/02/21/qbot-and-zerologon-lead-to-full-domain-compromise/