Uncommon Microsoft Office Trusted Location Added

Title: Uncommon Microsoft Office Trusted Location Added
Status: test
Description:Detects changes to registry keys related to "Trusted Location" of Microsoft Office where the path is set to something uncommon. Attackers might add additional trusted locations to avoid macro security restrictions.
References:
  -Internal Research
  -https://admx.help/?Category=Office2016&Policy=excel16.Office.Microsoft.Policies.Windows::L_TrustedLoc01
Author: Nasreddine Bencherchali (Nextron Systems)
Date: 2023-06-21
modified:2023-09-29
Tags:

• -'attack.persistence'
• -'attack.defense-impairment'
• -'attack.t1112'

Logsource:

• category: registry_set
• product: windows

Detection:
  selection:
    TargetObject|contains: 'Security\Trusted Locations\Location'
    TargetObject|endswith: '\Path'
  filter_exclude_known_paths:
    Details|contains:
      -'%APPDATA%\Microsoft\Templates'
      -'%%APPDATA%%\Microsoft\Templates'
      -'%APPDATA%\Microsoft\Word\Startup'
      -'%%APPDATA%%\Microsoft\Word\Startup'
      -':\Program Files (x86)\Microsoft Office\root\Templates\'
      -':\Program Files\Microsoft Office (x86)\Templates'
      -':\Program Files\Microsoft Office\root\Templates\'
      -':\Program Files\Microsoft Office\Templates\'

  filter_main_office_click_to_run:
    Image|contains: ':\Program Files\Common Files\Microsoft Shared\ClickToRun\'
    Image|endswith: '\OfficeClickToRun.exe'
  filter_main_office_apps:
    Image|contains:
      -':\Program Files\Microsoft Office\'
      -':\Program Files (x86)\Microsoft Office\'

  condition:selection and not 1 of filter_main_* and not 1 of filter_exclude_*
Falsepositives:
  -Other unknown legitimate or custom paths need to be filtered to avoid false positives
Level: high