Detection rules › Sigma
Suspicious Userinit Child Process
Detects a suspicious child process of userinit
Known false positives
- Administrative scripts
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Privilege Escalation | |
| Stealth |
Telemetry coverage
| Provider | Record / event type |
|---|---|
| Sysmon | Event ID 1: Process creation |
Rule body
title: Suspicious Userinit Child Process
id: b655a06a-31c0-477a-95c2-3726b83d649d
status: test
description: Detects a suspicious child process of userinit
references:
- https://twitter.com/SBousseaden/status/1139811587760562176
author: Florian Roth (Nextron Systems), Samir Bousseaden (idea)
date: 2019-06-17
modified: 2025-10-17
tags:
- attack.privilege-escalation
- attack.stealth
- attack.t1055
logsource:
category: process_creation
product: windows
detection:
selection:
ParentImage|endswith: '\userinit.exe'
filter_main_netlogon:
CommandLine|contains: '\netlogon\'
filter_main_explorer:
- Image|endswith: '\explorer.exe'
- OriginalFileName: 'explorer.exe'
- CommandLine: 'C:\Windows\Explorer.EXE'
filter_main_null:
Image: null
condition: selection and not 1 of filter_main_*
falsepositives:
- Administrative scripts
level: medium
Stages and Predicates
Stage 0: condition
selection and not 1 of filter_main_*Stage 1: selection
selection:
ParentImage|endswith: '\userinit.exe'
Stage 2: not filter_main_*
filter_main_netlogon:
CommandLine|contains: '\netlogon\'
filter_main_explorer:
- Image|endswith: '\explorer.exe'
- OriginalFileName: 'explorer.exe'
- CommandLine: 'C:\Windows\Explorer.EXE'
filter_main_null:
Image: null
Exclusions
The rule actively suppresses these predicates.
| Field | Kind | Excluded values | Search |
|---|---|---|---|
CommandLine | eq | C:\Windows\Explorer.EXE | excludes:CommandLine field:"CommandLine" value:"C:\Windows\Explorer.EXE" |
CommandLine | match | \netlogon\ | excludes:CommandLine field:"CommandLine" value:"\netlogon\" |
Image | ends_with | \explorer.exe | excludes:Image field:"Image" value:"\explorer.exe" |
Image | is_null | excludes:Image | |
OriginalFileName | eq | explorer.exe | excludes:OriginalFileName field:"OriginalFileName" value:"explorer.exe" |
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
ParentImage | ends_with |
| field:"ParentImage" kind:ends_with value:"\userinit.exe" |