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 Using an Alternate Name

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Microsoft Build Engine Using an Alternate Name

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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 positives

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

Investigation guide

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## 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

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process where event.type in ("start", "process_started") and
process.pe.original_file_name == "MSBuild.exe" and not process.name
: "MSBuild.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: Masquerading
- ID: T1036
- Reference URL: https://attack.mitre.org/techniques/T1036/

Rule version history

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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)"

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