Suspicious ShellExec_RunDLL Call Via Ordinal

Title: Suspicious ShellExec_RunDLL Call Via Ordinal
Status: experimental
Description:Detects suspicious call to the "ShellExec_RunDLL" exported function of SHELL32.DLL through the ordinal number to launch other commands. Adversary might only use the ordinal number in order to bypass existing detection that alert on usage of ShellExec_RunDLL on CommandLine.
References:
  -https://redcanary.com/blog/raspberry-robin/
  -https://www.microsoft.com/en-us/security/blog/2022/10/27/raspberry-robin-worm-part-of-larger-ecosystem-facilitating-pre-ransomware-activity/
  -https://github.com/SigmaHQ/sigma/issues/1009
  -https://strontic.github.io/xcyclopedia/library/shell32.dll-65DA072F25DE83D9F83653E3FEA3644D.html
Author: Swachchhanda Shrawan Poudel
Date: 2024-12-01
modified:None
Tags:

• -'attack.defense-evasion'
• -'attack.t1218.011'

Logsource:

• category: process_creation
• product: windows

Detection:
  selection_parent_img:
    ParentCommandLine|contains: 'SHELL32.DLL'
  selection_parent_ordinal:
    ParentCommandLine|contains:
      -'#568'
      -'#570'
      -'#572'
      -'#576'

  selection_susp_cli_parent:
    - ParentCommandLine|contains:
      - 'comspec'
      - 'iex'
      - 'Invoke-'
      - 'msiexec'
      - 'odbcconf'
      - 'regsvr32'
    - ParentCommandLine|contains:
      - '\Desktop\'
      - '\ProgramData\'
      - '\Temp\'
      - '\Users\Public\'
  selection_susp_child_img:
    Image|endswith:
      -'\bash.exe'
      -'\bitsadmin.exe'
      -'\cmd.exe'
      -'\cscript.exe'
      -'\curl.exe'
      -'\mshta.exe'
      -'\msiexec.exe'
      -'\msxsl.exe'
      -'\odbcconf.exe'
      -'\powershell.exe'
      -'\pwsh.exe'
      -'\regsvr32.exe'
      -'\schtasks.exe'
      -'\wmic.exe'
      -'\wscript.exe'

  condition:all of selection_parent_* and 1 of selection_susp_*
Falsepositives:
  -Unknown
Level: high