Microsoft Build Engine Started by a System Process

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Microsoft Build Engine Started by a System Process

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An instance of MSBuild, the Microsoft Build Engine, was started by Explorer or the WMI (Windows Management Instrumentation) subsystem. This behavior is unusual and is sometimes used by malicious payloads.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.*
  • logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Defense Evasion

Version: 10 (version history)

Added (Elastic Stack release): 7.7.0

Last modified (Elastic Stack release): 8.2.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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The Build Engine is commonly used by Windows developers but use by non-engineers is unusual.

Investigation guide

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## Config

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.

Rule query

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process where event.type in ("start", "process_started") and
process.name : "MSBuild.exe" and process.parent.name :
("explorer.exe", "wmiprvse.exe")

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 10 (8.2.0 release)
  • Formatting only
Version 9 (7.16.0 release)
  • Formatting only
Version 8 (7.13.0 release)
  • Updated query, changed from:

    event.category:process and event.type:(start or process_started) and
    process.name:MSBuild.exe and process.parent.name:(explorer.exe or
    wmiprvse.exe)
Version 7 (7.12.0 release)
  • Formatting only
Version 6 (7.11.2 release)
  • Formatting only
Version 5 (7.11.0 release)
  • Formatting only
Version 4 (7.10.0 release)
  • Formatting only
Version 3 (7.9.1 release)
  • Formatting only
Version 2 (7.9.0 release)
  • Updated query, changed from:

    process.name:MSBuild.exe and process.parent.name:(explorer.exe or
    wmiprvse.exe) and event.action:"Process Create (rule: ProcessCreate)"