title: Suspicious Serv-U Process Pattern
author: Florian Roth
date: 2021/07/14
description: Detects a suspicious process pattern which could be a sign of an exploited
    Serv-U service
detection:
    SELECTION_1:
        EventID: 1
    SELECTION_10:
        Image: '*\regsvr32.exe'
    SELECTION_11:
        Image: '*\wmic.exe'
    SELECTION_12:
        Image: '*\mshta.exe'
    SELECTION_13:
        Image: '*\rundll32.exe'
    SELECTION_14:
        Image: '*\msiexec.exe'
    SELECTION_15:
        Image: '*\forfiles.exe'
    SELECTION_16:
        Image: '*\scriptrunner.exe'
    SELECTION_2:
        ParentImage: '*\Serv-U.exe'
    SELECTION_3:
        Image: '*\cmd.exe'
    SELECTION_4:
        Image: '*\powershell.exe'
    SELECTION_5:
        Image: '*\wscript.exe'
    SELECTION_6:
        Image: '*\cscript.exe'
    SELECTION_7:
        Image: '*\sh.exe'
    SELECTION_8:
        Image: '*\bash.exe'
    SELECTION_9:
        Image: '*\schtasks.exe'
    condition: (SELECTION_1 and SELECTION_2 and (SELECTION_3 or SELECTION_4 or SELECTION_5
        or SELECTION_6 or SELECTION_7 or SELECTION_8 or SELECTION_9 or SELECTION_10
        or SELECTION_11 or SELECTION_12 or SELECTION_13 or SELECTION_14 or SELECTION_15
        or SELECTION_16))
falsepositives:
- Legitimate uses in which users or programs use the SSH service of Serv-U for remote
    command execution
id: 58f4ea09-0fc2-4520-ba18-b85c540b0eaf
level: critical
logsource:
    category: process_creation
    product: windows
references:
- https://www.microsoft.com/security/blog/2021/07/13/microsoft-discovers-threat-actor-targeting-solarwinds-serv-u-software-with-0-day-exploit/
status: experimental
tags:
- attack.credential_access
- cve.2021.35211
yml_filename: win_susp_servu_process_pattern.yml
yml_path: /Users/user/Documents/YamatoSecurity/sigma/rules/windows/process_creation