IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.
« Microsoft Build Engine Started by a System Process Microsoft Build Engine Using an Alternate Name »
Elastic Docs ›Elastic Security Solution [8.2] ›Detections and alerts ›Prebuilt rule reference

Microsoft Build Engine Started by an Office Application

edit

Microsoft Build Engine Started by an Office Application

edit

An instance of MSBuild, the Microsoft Build Engine, was started by Excel or Word. This is unusual behavior for the Build Engine and could have been caused by an Excel or Word document executing a malicious script payload.

Rule type: eql

Rule indices:

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

Severity: high

Risk score: 73

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: 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

edit

The Build Engine is commonly used by Windows developers but use by non-engineers is unusual. It is quite unusual for this program to be started by an Office application like Word or Excel.

Investigation guide

edit
## 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

edit
process where event.type in ("start", "process_started") and
process.name : "MSBuild.exe" and process.parent.name :
("eqnedt32.exe", "excel.exe",
"fltldr.exe", "msaccess.exe",
"mspub.exe", "outlook.exe",
"powerpnt.exe", "winword.exe" )

Threat mapping

edit

Framework: MITRE ATT&CKTM

Rule version history

edit
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:(eqnedt32.exe or
excel.exe or fltldr.exe or msaccess.exe or mspub.exe or outlook.exe or
powerpnt.exe or winword.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:(eqnedt32.exe or
excel.exe or fltldr.exe or msaccess.exe or mspub.exe or outlook.exe or
powerpnt.exe or winword.exe) and event.action: "Process Create (rule:
ProcessCreate)"
« Microsoft Build Engine Started by a System Process Microsoft Build Engine Using an Alternate Name »