wmi_permanent_event_subscription___sysmon.yml

name: WMI Permanent Event Subscription - Sysmon
id: ad05aae6-3b2a-4f73-af97-57bd26cee3b9
version: 2
date: '2023-11-07'
author: Rico Valdez, Michael Haag, Splunk
status: production
type: TTP
description: 'This analytic looks for the creation of WMI permanent event subscriptions.
  The following analytic identifies the use of WMI Event Subscription to establish
  persistence or perform privilege escalation.  WMI can be used to install event filters,
  providers, consumers, and bindings that execute code when a defined event occurs.
  WMI subscription execution is proxied by the WMI Provider Host process (WmiPrvSe.exe)
  and thus may result in elevated SYSTEM privileges. This analytic is restricted by
  commonly added process execution and a path. If the volume is low enough, remove
  the values and flag on any new subscriptions.

  All event subscriptions have three components 

  1. Filter - WQL Query for the events we want. EventID = 19 

  1. Consumer - An action to take upon triggering the filter. EventID = 20 

  1. Binding - Registers a filter to a consumer. EventID = 21 

  Monitor for the creation of new WMI EventFilter, EventConsumer, and FilterToConsumerBinding.
  It may be pertinent to review all 3 to identify the flow of execution. In addition,
  EventCode 4104 may assist with any other PowerShell script usage that registered
  the subscription.'
data_source:
- Sysmon EventID 21
search: '`sysmon` EventCode=21 | rename host as dest | table _time, dest, user, Operation,
  EventType, Query, Consumer, Filter | `wmi_permanent_event_subscription___sysmon_filter`'
how_to_implement: To successfully implement this search, you must be collecting Sysmon
  data using Sysmon version 6.1 or greater and have Sysmon configured to generate
  alerts for WMI activity (eventID= 19, 20, 21). In addition, you must have at least
  version 6.0.4 of the Sysmon TA installed to properly parse the fields.
known_false_positives: Although unlikely, administrators may use event subscriptions
  for legitimate purposes.
references:
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1546.003/T1546.003.md
- https://www.eideon.com/2018-03-02-THL03-WMIBackdoors/
- https://github.com/trustedsec/SysmonCommunityGuide/blob/master/chapters/WMI-events.md
- https://in.security/2019/04/03/an-intro-into-abusing-and-identifying-wmi-event-subscriptions-for-persistence/
tags:
  analytic_story:
  - Suspicious WMI Use
  asset_type: Endpoint
  confidence: 100
  impact: 30
  message: WMI Permanent Event Subscription detected on $dest$ by $user$
  mitre_attack_id:
  - T1546.003
  - T1546
  observable:
  - name: dest
    type: Endpoint
    role:
    - Victim
  - name: user
    type: User
    role:
    - Victim
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - EventCode
  - host
  - user
  - Operation
  - EventType
  - Query
  - Consumer
  - Filter
  risk_score: 30
  security_domain: endpoint
tests:
- name: True Positive Test
  attack_data:
  - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1546.003/atomic_red_team/windows-sysmon.log
    source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
    sourcetype: xmlwineventlog