Researchers in Germany have invented a new hack that can allow someone to break the encryption of PDF files and access their content. The attack, called PDFex, can allow an attacker to view the content of a PDF file without the public key or password encrypting it. The team published a report online detailing the attack, which encompasses two main techniques. They evaluated the hacks against two types of applications commonly used desktop applications and online validation services. PDFex can use any signed PDF document and create a document which contains arbitrary content in the name of the signing user, company, ministry or state
Source: https://threatpost.com/hack-breaks-pdf-encryption/148834/