Suspicious Scripting in a WMI Consumer — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems), Jonhnathan Ribeiro. Source status: test; severity: high. Source dates: 2019-04-15 / 2023-09-09.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 4b2f24870af12f0e885698edd46e1363dc5154c0e1dcf1950f95b6974c3c7688

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: Suspicious Scripting in a WMI Consumer
id: fe21810c-2a8c-478f-8dd3-5a287fb2a0e0
status: test
description: Detects suspicious commands that are related to scripting/powershell in WMI Event Consumers
references:
    - https://in.security/an-intro-into-abusing-and-identifying-wmi-event-subscriptions-for-persistence/
    - https://github.com/Neo23x0/signature-base/blob/615bf1f6bac3c1bdc417025c40c073e6c2771a76/yara/gen_susp_lnk_files.yar#L19
    - https://github.com/RiccardoAncarani/LiquidSnake
author: Florian Roth (Nextron Systems), Jonhnathan Ribeiro
date: 2019-04-15
modified: 2023-09-09
tags:
    - attack.execution
    - attack.t1059.005
logsource:
    product: windows
    category: wmi_event
detection:
    selection_destination:
        - Destination|contains|all:
              - 'new-object'
              - 'net.webclient'
              - '.downloadstring'
        - Destination|contains|all:
              - 'new-object'
              - 'net.webclient'
              - '.downloadfile'
        - Destination|contains:
              - ' iex('
              - ' -nop '
              - ' -noprofile '
              - ' -decode '
              - ' -enc '
              - 'WScript.Shell'
              - 'System.Security.Cryptography.FromBase64Transform'
    condition: selection_destination
falsepositives:
    - Legitimate administrative scripts
level: high

Original YAML and metadata in JSON

False positives

• Legitimate administrative scripts

Source references

• https://in.security/an-intro-into-abusing-and-identifying-wmi-event-subscriptions-for-persistence/
• https://github.com/Neo23x0/signature-base/blob/615bf1f6bac3c1bdc417025c40c073e6c2771a76/yara/gen_susp_lnk_files.yar#L19
• https://github.com/RiccardoAncarani/LiquidSnake