Office Macro File Creation From Suspicious Process — Sigma Rule

{
  "category": "file_event",
  "product": "windows",
  "definition": "Requirements: The \"ParentImage\" field is not available by default on EID 11 of Sysmon logs. To be able to use this rule to the full extent you need to enriche the log with additional ParentImage data"
}

title: Office Macro File Creation From Suspicious Process
id: b1c50487-1967-4315-a026-6491686d860e
status: test
description: Detects the creation of a office macro file from a a suspicious process
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1566.001/T1566.001.md
    - https://learn.microsoft.com/en-us/deployoffice/compat/office-file-format-reference
author: frack113, Nasreddine Bencherchali (Nextron Systems)
date: 2022-01-23
modified: 2023-02-22
tags:
    - attack.initial-access
    - attack.t1566.001
logsource:
    category: file_event
    product: windows
    definition: 'Requirements: The "ParentImage" field is not available by default on EID 11 of Sysmon logs. To be able to use this rule to the full extent you need to enriche the log with additional ParentImage data'
detection:
    selection_cmd:
        - Image|endswith:
              - '\cscript.exe'
              - '\mshta.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
              - '\wscript.exe'
        # Note: ParentImage is a custom field and is not available by default on Sysmon EID 11
        - ParentImage|endswith:
              - '\cscript.exe'
              - '\mshta.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
              - '\wscript.exe'
    selection_ext:
        TargetFilename|endswith:
            - '.docm'
            - '.dotm'
            - '.xlsm'
            - '.xltm'
            - '.potm'
            - '.pptm'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high