Potentially Suspicious Office Document Executed From Trusted Location — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2023-06-21 / 2023-10-18.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: d51d62d8ce6fb3a71ac34eb66c2d4f91d7a9debfe6b29abf96251ca02cd11b21

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: Potentially Suspicious Office Document Executed From Trusted Location
id: f99abdf0-6283-4e71-bd2b-b5c048a94743
status: test
description: Detects the execution of an Office application that points to a document that is located in a trusted location. Attackers often used this to avoid macro security and execute their malicious code.
references:
    - Internal Research
    - https://twitter.com/Max_Mal_/status/1633863678909874176
    - https://techcommunity.microsoft.com/t5/microsoft-365-blog/new-security-hardening-policies-for-trusted-documents/ba-p/3023465
    - https://twitter.com/_JohnHammond/status/1588155401752788994
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-06-21
modified: 2023-10-18
tags:
    - attack.stealth
    - attack.t1202
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        # Note: we add a parent shell to reduce FP. Add additional 3rd party shells that you might use
        ParentImage|endswith:
            - '\explorer.exe'
            - '\dopus.exe'
    selection_img:
        - Image|endswith:
              - '\EXCEL.EXE'
              - '\POWERPNT.EXE'
              - '\WINWORD.exe'
        - OriginalFileName:
              - 'Excel.exe'
              - 'POWERPNT.EXE'
              - 'WinWord.exe'
    selection_trusted_location:
        CommandLine|contains:
            # Note: these are the default locations. Admins/Users could add additional ones that you need to cover
            - '\AppData\Roaming\Microsoft\Templates'
            - '\AppData\Roaming\Microsoft\Word\Startup\'
            - '\Microsoft Office\root\Templates\'
            - '\Microsoft Office\Templates\'
    filter_main_dotx:
        # Note: We add this filter to avoid curious people clicking on template files
        CommandLine|endswith:
            - '.dotx'
            - '.xltx'
            - '.potx'
    condition: all of selection_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• Internal Research (source note; no public URL supplied)
• https://twitter.com/Max_Mal_/status/1633863678909874176
• https://techcommunity.microsoft.com/t5/microsoft-365-blog/new-security-hardening-policies-for-trusted-documents/ba-p/3023465
• https://twitter.com/_JohnHammond/status/1588155401752788994