This post is a writeup for a challenge I was working on during justCTF 2023. I didn’t solve it during the competition, unfortunately. But I decided to take a look at it afterwards, as it seemed interesting! (and I also needed some rev challenge for a class in the university :D) Description Some time ago I hosted a service that allowed me to do calculations on my computer. One day I noticed someone was executing the same code over and over again. Read more...

TL;DR: I got pissed with HPLIP not working, then the HP Smart app requiring account registration and reverse engineered the network communication and the HP Smart app to develop a tool called HPSimpleScan written in Go, that can be used to scan (not only) from this printer. In the process I’ve written a Kaitai Struct definition of the long-forgotten DIME format and contributed it to the Kaitai Struct formats repo. Read more...