en-US windows user

Trust logic for file attachments

Verified with Windows 11 25H2 — updated on July 30, 2026

Windows 11 25H2

Supported on: At least Windows XP Professional with SP2

Path in the GPO console

User Configuration\Administrative Templates\Windows Components\Attachment Manager

Description

This policy setting allows you to configure the logic that Windows uses to determine the risk for file attachments. Preferring the file handler instructs Windows to use the file handler data over the file type data. For example, trust notepad.exe, but don't trust .txt files. Preferring the file type instructs Windows to use the file type data over the file handler data. For example, trust .txt files, regardless of the file handler. Using both the file handler and type data is the most restrictive option. Windows chooses the more restrictive recommendation which will cause users to see more trust prompts than choosing the other options. If you enable this policy setting, you can choose the order in which Windows processes risk assessment data. If you disable this policy setting, Windows uses its default trust logic, which prefers the file handler over the file type. If you do not configure this policy setting, Windows uses its default trust logic, which prefers the file handler over the file type.

Registry

HKCU Software\Microsoft\Windows\CurrentVersion\Policies\Attachments

More options available

Options

Determine risk by
UseTrustedHandlers enum
  • Preferring the file handler -> 2 (default)
  • Looking at the file handler and type -> 3
  • Preferring the file type -> 1

MDM / Intune (CSP)

./User/Vendor/MSFT/Policy/Config/ADMX_AttachmentManager/AM_EstimateFileHandlerRisk
User Since Windows 10, version 2004 with KB5005101 [10.0.19041.1202] and later | Windows 10, version 20H2 with KB5005101 [10.0.19042.1202] and later | Windows 10, version 21H1 with KB5005101 [10.0.19043.1202] and later | Windows 11, version 21H2 [10.0.22000] and later Official mapping (Microsoft Learn)

Microsoft Learn documentation Mapping data: Microsoft Learn (CC BY 4.0)

Export Builder

BETA

Configure the state, scope and options, then generate .reg, PowerShell, Intune and SCCM outputs — or add the setting to a multi-setting collection.

These exports write the registry — this is not a managed GPO.

.reg file

Windows Registry Editor Version 5.00

; Exported from gporais.com
; Policy: Trust logic for file attachments
; State: Enabled
; Supported on: At least Windows XP Professional with SP2

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments]
"UseTrustedHandlers"=dword:00000002
More formats (PowerShell, Intune, SCCM)

PowerShell

# Exported from gporais.com
# Policy: Trust logic for file attachments
# State: Enabled
# Supported on: At least Windows XP Professional with SP2
# Warning: In SYSTEM context (the Intune default), HKCU targets the SYSTEM profile. Run this script using the logged-on credentials.

$path = 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'UseTrustedHandlers' -Value 2 -Type DWord

Building a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.

Open the Builder

Embed this policy on your site

What to embed
Theme

Adds one script line: the theme follows your site’s appearance and the height fits the content. If your site blocks scripts, the embed follows the visitor’s system theme.

Preview