Let's get back to work, and as Gynvael started streaming again, his mission should be great start.
MISSION 010 goo.gl/oAdvWe DIFFICULTY: ███░░░░░░░ [3/10] ┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅┅ We've received PDF document, where apparently there's a hidden message. Would you help us find it? https://goo.gl/wgt94W Good luck!
I started this challenge by looking at the file with a hex editor.
After a few moments of searching, I've found the JFIF segment and so, the whole structure of JPG file. From that moment, I think we'll be able to extract it from the PDF and somehow recreate it.
Quick peek at Wikipedia showed that whole JPG file is placed between
FF DA and
FF D9 codes.
|JFIF file structure|
||Start of Image|
||optional, see below|
|… additional marker segments
(for example SOF, DHT, COM)
||Start of Scan|
|compressed image data|
||End of Image|
Now let's copy everything between these segments and add to a new file.
Last step is to save this file as JPG image. By the way, here's the flag ;)
Keep learning and stay safe! ~ W3ndige