One of the main ways malware spreads these days is via Office documents and macros. Some malware are known to utilise bugs in Adobe Flash and macros, and use Office documents to invoke those bugs and cause infection.
The attachment preview feature in Microsoft Outlook can also expose the user to malware, by unknowingly running preview of the malware Office attachment, and cause the malware infection to start.
Fortunately , the attachment preview feature can be disabled in Outlook.
I have created a simple console tool (C# EXE file) to help change this setting in registry.
I have also provided below the registry setting that needs to be changed to disable it.
Or, you can simply go to the Outlook settings to disable it:
i) In Outlook , go to File > Options > Trust Center > Trust Center Settings, and then select Attachment Handling.
ii) To turn off all attachment previewers, click Turn off Attachment Preview and click OK.
This tool helps enable / disable email attachment preview function in Microsoft Outlook.
It is useful as it can help eliminate malware execution by attachment preview of malware infected Office documents/macro via unpatched Office/Adobe Flash bugs.
Please note the following :
a) The registry script & C# tool below works on Microsoft Outlook 2016, 2013 & 2010 only. It does not work on Microsoft Outlook 365.
b) The C# tool below works on Windows 7 & Windows 10 PCs, and should be "run as administrator".
c) It requires Microsoft .NET Framework 3.5 or above.
Registry setting to disable Outlook attachment preview :
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Policies\Microsoft\office\16.0\outlook\preferences]
"disableattachmentpreviewing"=dword:00000001
[HKEY_CURRENT_USER\Software\Policies\Microsoft\office\15.0\outlook\preferences]
"disableattachmentpreviewing"=dword:00000001
[HKEY_CURRENT_USER\Software\Policies\Microsoft\office\14.0\outlook\preferences]
"disableattachmentpreviewing"=dword:00000001
You can download the C# tool here:
File name : Outlook_disable_attachment_preview.exe
MD5 checksum value :761716ed7ab1bebb197aa5f84a0625e7
