Microsoft Build Engine Started an Unusual Process

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Microsoft Build Engine Started an Unusual Process

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An instance of the Microsoft Build Engine (MSBuild) started a PowerShell script or the Visual C# command line compiler. This technique is sometimes used to deploy a malicious payload using MSBuild.

Rule type: eql

Rule indices:

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

Severity: low

Risk score: 21

Runs every: 5m

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

Maximum alerts per execution: 100

References:

Tags:

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

Version: 9

Rule authors:

  • Elastic

Rule license: Elastic License v2

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.parent.name : "MSBuild.exe" and
  process.name : ("csc.exe", "iexplore.exe", "powershell.exe")

Framework: MITRE ATT&CKTM