WMI Persistence - Script Event Consumer — Sigma Rule

Rule metadata and linked tags

Author: Thomas Patzke. Source status: test; severity: medium. Source dates: 2018-03-07 / 2022-10-11.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 1a4f70652f2b3c811152d4a52535b925e720a3fd6fd1116c48cd9a31170f5108

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: WMI Persistence - Script Event Consumer
id: ec1d5e28-8f3b-4188-a6f8-6e8df81dc28e
status: test
description: |
    Detects the execution of a script event consumer. When scrcons.exe launches, it does so in response to the creation of an ActiveScriptEventConsumer instance
    and will execute registered JScript or VBScript code as a result.
    Script event consumers are a built-in Windows Management Instrumentation (WMI) class that
    automatically executes a predefined script (in VBScript or JScript) whenever a specific system event occurs.
    Adversaries often abuse script event consumers to maintain persistence on a compromised host
    by executing a malicious script whenever a specific event occurs.
references:
    - https://redcanary.com/blog/threat-detection/child-processes/
    - https://www.eideon.com/2018-03-02-THL03-WMIBackdoors/
author: Thomas Patzke
date: 2018-03-07
modified: 2022-10-11
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1546.003
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image: C:\WINDOWS\system32\wbem\scrcons.exe
        ParentImage: C:\Windows\System32\svchost.exe
    condition: selection
falsepositives:
    - Legitimate event consumers
    - Dell computers on some versions register an event consumer that is known to cause false positives when brightness is changed by the corresponding keyboard button
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate event consumers
• Dell computers on some versions register an event consumer that is known to cause false positives when brightness is changed by the corresponding keyboard button

Source references

• https://redcanary.com/blog/threat-detection/child-processes/
• https://www.eideon.com/2018-03-02-THL03-WMIBackdoors/