Custom WMI (Windows Management Instrumentation) input package

Serverless Observability Serverless Security Stack 9.1.0


Version	0.0.2 Beta (View all)
Subscription level What's this?	Basic
Developed by What's this?	Elastic

The Custom WMI Input integration reads metrics via Windows Management Instrumentation (WMI), a core management technology in the Windows operating system. By leveraging WMI Query Language (WQL), this integration allows you to extract detailed system information and metrics to monitor the health and performance of Windows systems.

This input leverages the Microsoft WMI library, a convenient wrapper around the GO-OLE library which allows to invoke the WMI API.

Requirements

This integration requires Elastic-Agent 8.19.0 or 9.1.0 and above.

Compatibility

This integration has been tested on the following platforms:

Operating System	Architecture
Microsoft Windows Server 2019 Datacenter	x64
Microsoft Windows 11 Pro	x64

WMI Query Language (WQL) support

This integration supports the execution of WQL queries, a SQL-like query language for retrieving information from WMI namespaces.

Currently, this input package supports queries with SELECT, FROM and WHERE clauses.

Warning: When working with WMI queries, it is the user’s responsibility to ensure that queries are safe, efficient, and do not cause unintended side effects. A notorious example of a problematic WMI class is Win32_Product. Read more in the related Windows documentation.

WMI arbitrator and query execution

Query execution is managed by the underlying WMI framework, specifically by the WMI arbitrator. The arbitrator is responsible for:

Scheduling and controlling query execution
Throttling or stopping queries based on system resource availability and conditions

There is no way to directly stop a query once it has started. To prevent Elastic Agent from waiting indefinitely for a query to return a result or fail, Elastic Agent has a timeout mechanism that stops waiting for query results after a specified timeout. This is controlled by the wmi.warning_threshold setting.

Note

While Elastic Agent stops waiting for the result, the underlying WMI query may continue running until the WMI arbitrator decides to stop execution.

WMI type support

The microsoft/wmi library internally uses the WMI Scripting API. This API, as per the official WMI documentation, does not provide direct type conversion for uint64, sint64, and datetime Common Information Model (CIM) types; instead, these values are returned as strings.

To ensure the correct data type is reported, Elastic Agent dynamically fetches the CIM type definitions for the properties of the WMI instance classes returned by the query, and then performs the necessary data type conversions.

To optimize performance and avoid repeatedly fetching these schema definitions for every row and every request, an LRU cache is utilized. This cache stores the schema definition for each WMI class-property pair encountered. For queries involving superclasses, such as CIM_LogicalDevice, the cache will populate with individual entries for each specific derived class (leaf of the class hierarchy) whose instances are returned by the query (for example, Win32_DiskDrive or Win32_NetworkAdapter).

Note: The properties of type CIM_Object (embedded objects) are not yet supported and are ignored.

Note: The properties of type CIM_Reference (references) used in WMI Association Classes are currently returned as strings as reported by the microsoft/wmi library.

Date fields mapping

Elastic Agent converts WMI properties of type "datetime" to timestamps, but these are serialized as strings in the output. Since date detection is disabled by default, these fields will be stored as strings unless explicitly mapped as dates. To ensure proper mapping, we recommend explicitly setting the mapping in the @custom template. Refer to Edit the Elasticsearch index template and Manage component templates for additional details.

Configuration

Option	Description	Default
`wmi.namespace`	The default WMI namespace used for queries. This can be overridden per query.	`"root\\cimv2"`
`wmi.warning_threshold`	The time threshold after which Elastic Agent will stop waiting for the query result and return control to the main flow of the program. A warning is logged indicating that the query execution has exceeded the threshold. Refer to WMI arbitrator and query execution for more details.	Equal to `period`
`wmi.include_queries`	If set to `true`, the query is added in the output document.	`false`
`wmi.include_query_class`	If set to `true`, the metricset includes the queried class. This is useful if superclasses are queried. The default value is `false`.	`false`
`wmi.include_null_properties`	If set to `true`, the output documents will include the properties that have a `null` value.	`false`
`wmi.include_empty_string_properties`	If set to `true`, the output documents will include the properties that are empty strings.	`false`
`wmi.max_rows_per_query`	Limits the number of rows returned by a single WMI query. The default value is `0`, which is a special value indicating that all fetched
results should be returned without a row limit.	`0`
`wmi.schema_cache_size`	The maximum number of WMI class-property pairs that can be cached per single query. Every query keeps its own separate cache. This cache helps improve performance when dealing with queries that involve inheritance hierarchies. Read more in WMI type support. For example, if a superclass is queried, the cache stores entries for each WMI concrete instance class (the leaves of the class hierarchy) and their associated properties. Therefore, querying a superclass that returns a result set containing instances of `10` different classes, each with `50` properties, will result in a cache size of `500` entries (`10×50`).	`1000`
`wmi.queries`	The list of queries to execute. The list cannot be empty. Refer to Query configuration for the format of the queries.	(required)

Query configuration

Each item in the queries list specifies a WMI query to perform.

Option	Description	Required/Default
`class`	The WMI class. Specifies the `FROM` clause in the query.	Required
`properties`	List of properties to return. Specifies the `SELECT` clause. Set to an empty list (default) to retrieve all available properties.	Default: empty list
`where`	The `WHERE` clause. Read more about the format in the related Windows documentation.	Optional
`namespace`	The WMI namespace for this query (overrides the global `namespace` value for this query).	Optional

Example

Example WQL query:

		SELECT Name, ProcessId, WorkingSetSize
FROM Win32_Process
WHERE Name = 'lsass.exe' AND WorkingSetSize > 104857600
		
	

Equivalent YAML configuration:

		- class: Win32_Process
  properties:
  - Name
  - ProcessId
  - WorkingSetSize
  where: "Name = 'lsass.exe' AND WorkingSetSize > 104857600"
		
	

Version	Details	Kibana version(s)
0.0.2	Enhancement (View pull request) WMI Input improve documentation	—
0.0.1	Enhancement (View pull request) WMI Input Package draft	—