Convert indexed Sigma rules into analyst-ready detections.

title: Qakbot Rundll32 Fake DLL Extension Execution
id: bfd34392-c591-4009-b938-9fd985a28b85
status: test
description: Detects specific process tree behavior of a "rundll32" execution where the DLL doesn't have the ".dll" extension. This is often linked with potential Qakbot activity.
references:
    - https://github.com/pr0xylife/Qakbot/
author: X__Junior (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2023-05-24
tags:
    - attack.defense-evasion
    - attack.execution
    - detection.emerging-threats
logsource:
    product: windows
    category: process_creation
detection:
    selection:
        ParentImage|endswith:
            # Note: Only add processes seen used by Qakbot to avoid collision with other strains of malware
            - '\cmd.exe'
            - '\cscript.exe'
            - '\curl.exe'
            - '\mshta.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\wscript.exe'
        Image|endswith: '\rundll32.exe'
        CommandLine|contains:
            # Note: Only add paths seen used by Qakbot to avoid collision with other strains of malware
            - ':\ProgramData\'
            - ':\Users\Public\'
            - '\AppData\Local\Temp\'
            - '\AppData\Roaming\'
    filter_main_extension:
        CommandLine|contains: '.dll'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unlikely
level: critical