PDF Stream Filters – Part 2

It is very interesting to study the ¬†obfuscation techniques used by the attackers in malicious PDF docs. As of my previous blog entry, one of the simplest, yet interesting obfuscation technique used is the cascading filtering. This basically means that the ¬†malicious JavaScript code is embedded below the multiple layers of encoded stream. In this […]

PDF Stream Filter – Part 1

One of the challenges in analyzing malicious PDF document is stream filtering. Malicious contents in PDF file are usually compressed with stream filtering thus making ¬†analysis a bit complicated. In a PDF document , stream object consists of stream dictionary, stream keyword, a sequence of bytes, and endstream keyword. A malicious content inside PDF file […]