Suspicious Spool Service Child Process

Title: Suspicious Spool Service Child Process
Status: test
Description:Detects suspicious print spool service (spoolsv.exe) child processes.
References:
  -https://github.com/microsoft/Microsoft-365-Defender-Hunting-Queries/blob/efa17a600b43c897b4b7463cc8541daa1987eeb4/Exploits/Print%20Spooler%20RCE/Suspicious%20Spoolsv%20Child%20Process.md
Author: Justin C. (@endisphotic), @dreadphones (detection), Thomas Patzke (Sigma rule)
Date: 2021-07-11
modified:2024-12-01
Tags:

• -'attack.execution'
• -'attack.t1203'
• -'attack.privilege-escalation'
• -'attack.t1068'

Logsource:

• category: process_creation
• product: windows

Detection:
  spoolsv:
    ParentImage|endswith: '\spoolsv.exe'
    IntegrityLevel:
      -'System'
      -'S-1-16-16384'

  suspicious_unrestricted:
    Image|endswith:
      -'\gpupdate.exe'
      -'\whoami.exe'
      -'\nltest.exe'
      -'\taskkill.exe'
      -'\wmic.exe'
      -'\taskmgr.exe'
      -'\sc.exe'
      -'\findstr.exe'
      -'\curl.exe'
      -'\wget.exe'
      -'\certutil.exe'
      -'\bitsadmin.exe'
      -'\accesschk.exe'
      -'\wevtutil.exe'
      -'\bcdedit.exe'
      -'\fsutil.exe'
      -'\cipher.exe'
      -'\schtasks.exe'
      -'\write.exe'
      -'\wuauclt.exe'
      -'\systeminfo.exe'
      -'\reg.exe'
      -'\query.exe'

  suspicious_net:
    Image|endswith:
      -'\net.exe'
      -'\net1.exe'

  suspicious_net_filter:
    CommandLine|contains: 'start'
  suspicious_cmd:
    Image|endswith: '\cmd.exe'
  suspicious_cmd_filter:
    CommandLine|contains:
      -'.spl'
      -'route add'
      -'program files'

  suspicious_netsh:
    Image|endswith: '\netsh.exe'
  suspicious_netsh_filter:
    CommandLine|contains:
      -'add portopening'
      -'rule name'

  suspicious_powershell:
    Image|endswith:
      -'\powershell.exe'
      -'\pwsh.exe'

  suspicious_powershell_filter:
    CommandLine|contains: '.spl'
  suspicious_rundll32_img:
Image|endswith:'\rundll32.exe' OriginalFileName:'RUNDLL32.EXE'   suspicious_rundll32_cli:
    CommandLine|endswith: 'rundll32.exe'
  condition:spoolsv and ( suspicious_unrestricted or (suspicious_net and not suspicious_net_filter) or (suspicious_cmd and not suspicious_cmd_filter) or (suspicious_netsh and not suspicious_netsh_filter) or (suspicious_powershell and not suspicious_powershell_filter) or all of suspicious_rundll32_* )
Falsepositives:
  -Unknown
Level: high