“OMG WTF PDF
What you didn’t know about Acrobat”
▻https://media.ccc.de/v/27c3-4221-en-omg_wtf_pdf
Ambiguities in the PDF specification means that no two PDF parsers will see a file in the same way. This leads to many opportunities for exploit obfuscation.
A very interesting look into the specs of a pdf. It turns out it’s an insane mishmash of all sorts of things, with all sorts of weird concurrent conventions.