InfoPath provides three security levels for forms: Restricted, Domain, and Full Trust. These security levels determine whether a form is allowed to access data in other domains, or access files and settings on your computer.
Forms that are fully trusted use the Full Trust security level, which can be applied only if the form template that the form is based on is digitally signed by using a trusted root certificate, or if the form template is installed on your computer by using a customized setup program.
Because fully trusted forms have a Full Trust security level, they can access files and settings on your computer. To prevent such access, use the following procedure:
On the Tools menu, click Trust Center.
At the bottom of the Trust Center dialog box, clear the Allow fully trusted forms to run on my computer check box.
Note: After you do this, you will no longer be able to open a fully trusted form.
Security Note: To help protect the security of your computer and data, use caution when you install forms or allow forms to access files and settings on your computer. You should install or open forms only from trusted sources, and you should question all messages, attachments, and files that you receive from unexpected sources. If a file has an unusual file name, time stamp, file name extension, file size, or other property, do not open that file.