Office Macro File Download — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: low. Source dates: 2022-01-23 / 2025-10-29.

{
  "category": "file_event",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 51e427a9c78b91506f789b74f7978f8c5862395f1f691907b27e940d4cb819a8

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Office Macro File Download
id: 0e29e3a7-1ad8-40aa-b691-9f82ecd33d66
related:
    - id: 91174a41-dc8f-401b-be89-7bfc140612a0
      type: similar
status: test
description: |
    Detects the creation of a new office macro files on the system via an application (browser, mail client).
    This can help identify potential malicious activity, such as the download of macro-enabled documents that could be used for exploitation.
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: Nasreddine Bencherchali (Nextron Systems)
date: 2022-01-23
modified: 2025-10-29
tags:
    - attack.initial-access
    - attack.t1566.001
logsource:
    category: file_event
    product: windows
detection:
    selection_processes:
        Image|endswith:
            # Email clients
            - '\RuntimeBroker.exe' # Windows Email clients uses RuntimeBroker to create the files
            - '\outlook.exe'
            - '\thunderbird.exe'
            # Browsers
            - '\brave.exe'
            - '\chrome.exe'
            - '\firefox.exe'
            - '\iexplore.exe'
            - '\maxthon.exe'
            - '\MicrosoftEdge.exe'
            - '\msedge.exe'
            - '\msedgewebview2.exe'
            - '\opera.exe'
            - '\safari.exe'
            - '\seamonkey.exe'
            - '\vivaldi.exe'
            - '\whale.exe'
    selection_ext:
        - TargetFilename|endswith:
              - '.docm'
              - '.dotm'
              - '.xlsm'
              - '.xltm'
              - '.potm'
              - '.pptm'
        - TargetFilename|contains:
              - '.docm:Zone'
              - '.dotm:Zone'
              - '.xlsm:Zone'
              - '.xltm:Zone'
              - '.potm:Zone'
              - '.pptm:Zone'
    condition: all of selection_*
falsepositives:
    - Legitimate macro files downloaded from the internet
    - Legitimate macro files sent as attachments via emails
level: low

Original YAML and metadata in JSON

False positives

• Legitimate macro files downloaded from the internet
• Legitimate macro files sent as attachments via emails

Source 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