Suspicious Spool Service Child Process

title: Suspicious Spool Service Child Process
id: dcdbc940-0bff-46b2-95f3-2d73f848e33b
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