2. External Application Launching - Believe it or not, Reader can launch other application and have them display their content within the PDF viewer. This is enabled by default! Turns out there is a hack to change the contents of the warning dialog to use social engineering to deceive the user into allowing the application to launch and even launch arbitrary code to take over your computer. This is easily avoidable by disabling it – if you ever do need it, Adobe Reader will tell you that it is disabled and you can have the opportunity to re-enable it. To do so,go to the Preferences dialog and click on the Trust Manager category. Uncheck “Allow opening of non-PDF file attachments with external applications.” Please.