sigmamediumHunting

Cscript/Wscript Potentially Suspicious Child Process

Detects potentially suspicious child processes of Wscript/Cscript. These include processes such as rundll32 with uncommon exports or PowerShell spawning rundll32 or regsvr32. Malware such as Pikabot and Qakbot were seen using similar techniques as well as many others.

Detection Query

selection_parent:
  ParentImage|endswith:
    - \wscript.exe
    - \cscript.exe
selection_cli_script_main:
  Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \pwsh.exe
selection_cli_script_option_mshta:
  CommandLine|contains|all:
    - mshta
    - http
selection_cli_script_option_other:
  CommandLine|contains:
    - rundll32
    - regsvr32
    - msiexec
selection_cli_standalone:
  Image|endswith: \rundll32.exe
filter_main_rundll32_known_exports:
  Image|endswith: \rundll32.exe
  CommandLine|contains:
    - UpdatePerUserSystemParameters
    - PrintUIEntry
    - ClearMyTracksByProcess
condition: selection_parent and ( selection_cli_standalone or
  (selection_cli_script_main and 1 of selection_cli_script_option_*) ) and not 1
  of filter_main_*

Author

Nasreddine Bencherchali (Nextron Systems), Alejandro Houspanossian ('@lekz86')

Created

2023-05-15

Data Sources

windowsProcess Creation Events

Platforms

windows

References

Tags

attack.execution

Raw Content

title: Cscript/Wscript Potentially Suspicious Child Process
id: b6676963-0353-4f88-90f5-36c20d443c6a
status: test
description: |
    Detects potentially suspicious child processes of Wscript/Cscript. These include processes such as rundll32 with uncommon exports or PowerShell spawning rundll32 or regsvr32.
    Malware such as Pikabot and Qakbot were seen using similar techniques as well as many others.
references:
    - Internal Research
    - https://github.com/pr0xylife/Pikabot/blob/fc58126127adf0f65e78f4eec59675523f48f086/Pikabot_30.10.2023.txt
    - https://github.com/pr0xylife/Pikabot/blob/fc58126127adf0f65e78f4eec59675523f48f086/Pikabot_22.12.2023.txt
author: Nasreddine Bencherchali (Nextron Systems), Alejandro Houspanossian ('@lekz86')
date: 2023-05-15
modified: 2024-01-02
tags:
    - attack.execution
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|endswith:
            - '\wscript.exe'
            - '\cscript.exe'
    selection_cli_script_main:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
    # Note: Add other combinations that are suspicious
    selection_cli_script_option_mshta:
        CommandLine|contains|all:
            - 'mshta'
            - 'http'
    selection_cli_script_option_other:
        CommandLine|contains:
            - 'rundll32'
            - 'regsvr32'
            - 'msiexec'
    selection_cli_standalone:
        Image|endswith: '\rundll32.exe'
    filter_main_rundll32_known_exports:
        Image|endswith: '\rundll32.exe'
        CommandLine|contains:
            - 'UpdatePerUserSystemParameters'
            - 'PrintUIEntry'
            - 'ClearMyTracksByProcess'
    condition: selection_parent and ( selection_cli_standalone or (selection_cli_script_main and 1 of selection_cli_script_option_*) ) and not 1 of filter_main_*
falsepositives:
    - Some false positives might occur with admin or third party software scripts. Investigate and apply additional filters accordingly.
level: medium