Microsoft Build Engine Using an Alternate Nameedit

An instance of MSBuild, the Microsoft Build Engine, was started after being renamed. This is uncommon behavior and may indicate an attempt to run unnoticed or undetected.

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

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 positivesedit

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

Investigation guideedit

## 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 queryedit

process where event.type in ("start", "process_started") and
process.pe.original_file_name == "MSBuild.exe" and not process.name
: "MSBuild.exe"

Threat mappingedit

Framework: MITRE ATT&CKTM

Rule version historyedit

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.pe.original_file_name:MSBuild.exe and not process.name:
    MSBuild.exe
Version 7 (7.12.0 release)
  • Formatting only
Version 6 (7.11.2 release)
  • Formatting only
Version 5 (7.11.0 release)
  • Updated query, changed from:

    event.category:process and event.type:(start or process_started) and
    (process.pe.original_file_name:MSBuild.exe or
    winlog.event_data.OriginalFileName:MSBuild.exe) and not process.name:
    MSBuild.exe
Version 4 (7.10.0 release)
  • Updated query, changed from:

    event.category:process and event.type:(start or process_started) and
    (pe.original_file_name:MSBuild.exe or
    winlog.event_data.OriginalFileName:MSBuild.exe) and not process.name:
    MSBuild.exe
Version 3 (7.9.1 release)
  • Formatting only
Version 2 (7.9.0 release)
  • Updated query, changed from:

    (pe.original_file_name:MSBuild.exe or
    winlog.event_data.OriginalFileName: MSBuild.exe) and not process.name:
    MSBuild.exe and event.action: "Process Create (rule: ProcessCreate)"