Windows: Child Process Spawned with SYSTEM Integrity by LOCAL/NETWORK SERVICE Parent

Alert on Windows executions where a SYSTEM-integrity child is spawned by a LOCAL SERVICE or NETWORK SERVICE parent, excluding a specific rundll32 pattern.

FreeUnreviewedSigmahighv1

windows-child-process-spawned-with-system-integrity-by-local-network-service-par-590a5f4c

title: "Windows: Child Process Spawned with SYSTEM Integrity by LOCAL/NETWORK SERVICE Parent"
id: 52e53518-c385-41f8-9373-09877f096a6d
status: test
description: This rule flags Windows process creation events where a child process runs with SYSTEM integrity while the parent process is associated with LOCAL SERVICE or NETWORK SERVICE accounts. Such behavior can indicate attempts to escalate privileges by leveraging service-context processes to spawn or execute SYSTEM-level code. The detection relies on process creation telemetry including parent user and child user/ integrity level fields, and it excludes cases involving rundll32.exe with a DavSetCookie command-line fragment.
references:
  - https://speakerdeck.com/heirhabarov/hunting-for-privilege-escalation-in-windows-environment
  - https://foxglovesecurity.com/2016/09/26/rotten-potato-privilege-escalation-from-service-accounts-to-system/
  - https://github.com/antonioCoco/RogueWinRM
  - https://twitter.com/Cyb3rWard0g/status/1453123054243024897
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_susp_child_process_as_system_.yml
author: Teymur Kheirkhabarov, Roberto Rodriguez (@Cyb3rWard0g), Open Threat Research (OTR), Huntrule Team
date: 2019-10-26
modified: 2024-12-01
tags:
  - attack.privilege-escalation
  - attack.stealth
  - attack.t1134.002
logsource:
  category: process_creation
  product: windows
  definition: "Requirements: ParentUser field needs sysmon >= 13.30"
detection:
  selection:
    ParentUser|contains:
      - AUTHORI
      - AUTORI
    ParentUser|endswith:
      - \NETWORK SERVICE
      - \LOCAL SERVICE
    User|contains:
      - AUTHORI
      - AUTORI
    User|endswith:
      - \SYSTEM
      - \Système
      - \СИСТЕМА
    IntegrityLevel:
      - System
      - S-1-16-16384
  filter_rundll32:
    Image|endswith: \rundll32.exe
    CommandLine|contains: DavSetCookie
  condition: selection and not 1 of filter_*
falsepositives:
  - Unknown
level: high
license: DRL-1.1
related:
  - id: 590a5f4c-6c8c-4f10-8307-89afe9453a9d
    type: derived

What it detects

This rule flags Windows process creation events where a child process runs with SYSTEM integrity while the parent process is associated with LOCAL SERVICE or NETWORK SERVICE accounts. Such behavior can indicate attempts to escalate privileges by leveraging service-context processes to spawn or execute SYSTEM-level code. The detection relies on process creation telemetry including parent user and child user/ integrity level fields, and it excludes cases involving rundll32.exe with a DavSetCookie command-line fragment.

Known false positives

Unknown

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.