Suspicious macOS MS Office Child Process

Identifies suspicious child processes of frequently targeted Microsoft Office applications (Word, PowerPoint, and Excel). These child processes are often launched during exploitation of Office applications or by documents with malicious macros.

Rule type: eql

Rule indices:

logs-endpoint.events.*

Severity: medium

Risk score: 47

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.malwarebytes.com/cybercrime/2017/02/microsoft-office-macro-malware-targets-macs/

Tags:

Elastic
Host
macOS
Threat Detection
Initial Access

Version: 2 (version history)

Added (Elastic Stack release): 7.12.0

Last modified (Elastic Stack release): 7.13.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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process where event.type in ("start", "process_started") and
process.parent.name:("Microsoft Word", "Microsoft PowerPoint",
"Microsoft Excel") and process.name: ( "bash", "dash",
"sh", "tcsh", "csh", "zsh", "ksh", "fish",
"python*", "perl*", "php*", "osascript", "pwsh",
"curl", "wget", "cp", "mv", "base64", "launchctl"
) and /* noisy false positives related to product version discovery
and office errors reporting */ not process.args: (
"ProductVersion", "hw.model", "ioreg",
"ProductName", "ProductUserVisibleVersion",
"ProductBuildVersion", "/Library/Application
Support/Microsoft/MERP*/Microsoft Error
Reporting.app/Contents/MacOS/Microsoft Error Reporting" )

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
Technique:
- Name: Phishing
- ID: T1566
- Reference URL: https://attack.mitre.org/techniques/T1566/

Rule version history

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Version 2 (7.13.0 release)

Updated query, changed from:

process where event.type in ("start", "process_started") and
process.parent.name:("Microsoft Word", "Microsoft PowerPoint",
"Microsoft Excel") and process.name: ( "bash", "dash",
"sh", "tcsh", "csh", "zsh", "ksh", "fish",
"python*", "perl*", "php*", "osascript", "pwsh",
"curl", "wget", "cp", "mv", "base64", "launchctl"
)

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