Microsoft Build Engine Started an Unusual Process


Microsoft Build Engine Started an Unusual Processedit

An instance of MSBuild, the Microsoft Build Engine, started a PowerShell script or the Visual C# Command Line Compiler. This technique is sometimes used to deploy a malicious payload using the Build Engine.

Rule type: new_terms

Rule indices:

  • winlogbeat-*
  • 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



  • Domain: Endpoint
  • OS: Windows
  • Use Case: Threat Detection
  • Tactic: Defense Evasion
  • Tactic: Execution
  • Data Source: Elastic Defend

Version: 211

Rule authors:

  • Elastic

Rule license: Elastic License v2



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 version 8.2. Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate event.ingested to @timestamp. For more details on adding a custom ingest pipeline refer -

Rule queryedit

host.os.type:windows and event.category:process and event.type:start and"MSBuild.exe" or "msbuild.exe") and"csc.exe" or "iexplore.exe" or "powershell.exe")