IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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Microsoft Build Engine Started by an Office Application

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Microsoft Build Engine Started by an Office Application

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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: query

Rule indices:

winlogbeat-*
logs-endpoint.events.*

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:

https://blog.talosintelligence.com/2020/02/building-bypass-with-msbuild.html

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion

Version: 4 (version history)

Added (Elastic Stack release): 7.7.0

Last modified (Elastic Stack release): 7.10.0

Rule authors: Elastic

Rule license: Elastic License

Potential false positives

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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.

Rule query

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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)

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Trusted Developer Utilities Proxy Execution
- ID: T1127
- Reference URL: https://attack.mitre.org/techniques/T1127/
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
Technique:
- Name: Trusted Developer Utilities Proxy Execution
- ID: T1127
- Reference URL: https://attack.mitre.org/techniques/T1127/

Rule version history

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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)"

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