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Elastic Docs ›Elastic Security Solution [8.5] ›Detections and alerts ›Prebuilt rule reference

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 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: eql

Rule indices:

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

Severity: low

Risk score: 21

Runs every: 5 minutes

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: 101 (version history)

Added (Elastic Stack release): 7.7.0

Last modified (Elastic Stack release): 8.5.0

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. If a build system triggers this rule it can be exempted by process, user or host name.

Investigation guide

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Rule query
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process where event.type == "start" and process.parent.name :
"MSBuild.exe" and process.name : ("csc.exe", "iexplore.exe",
"powershell.exe")











Threat mapping
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Framework: MITRE ATT&CKTM














Rule version history
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Version 101 (8.5.0 release)








    

  • 

    Updated query, changed from:
    

    

    

    process where event.type in ("start", "process_started") and
process.parent.name : "MSBuild.exe" and process.name : ("csc.exe",
"iexplore.exe", "powershell.exe")
    

    

    • 









Version 11 (8.4.0 release)








    

  • 
Formatting only

    • 









Version 9 (8.2.0 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.parent.name:MSBuild.exe and process.name:(csc.exe or
iexplore.exe or powershell.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

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Version 3 (7.9.1 release)








    

  • 
Formatting only

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Version 2 (7.9.0 release)








    

  • 

    Updated query, changed from:
    

    

    

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

    

    • 




















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