Help:Security/PDF files/en

The PDF file format has certain security and privacy issues that you might want to consider before opening such files. PDF files can include complex interactive features which might trigger the PDF reader software to connect to the Internet and reveal the IP address and other personal information of the user to a third party. A malicious PDF author might use this functionality to connect network locations to wiki usernames or otherwise violate the privacy of the reader.

PDF has a complex internal structure which makes practically impossible to detect dangerous files; it is left to the privacy-conscious reader to take precautions. Whether a PDF file is able to expose private information depends on your choice of PDF reader software. In general, PDF readers with less functionality are safer; the native PDF readers built into the Firefox and Chrome web browsers are the safest choice.

Older versions of Adobe Acrobat and Adobe Reader, with their default settings, are not safe. Adobe Acrobat XI, DC, and newer versions all prompt the user before connecting to the Internet, unless you have manually changed Acrobat's trust settings.

Further reading:
 * Adobe documentation about security settings
 * Aniello Castiglione, Alfredo De Santis, Claudio Soriente: Security and privacy issues in the Portable Document Format