Sending large packets in SSH

I have been having troubles with a question where I had to test that an SSH implementation drops (or reject) packets greater than 262144. Thus, after reading the RFCs and the SSH protocol standard, I had only two solution I found is implement my own SSH protocol, or (easy and chose way) modify an existing implementation of SSH.If we look the RFC 4253 [1], which is the RFC of SSH, we have the following:We can send and receive a packet …

Basic Linux binary analysis tips

Tips and useful commands for analyse binaries from determining the file to debugging. The purpose of this post is have a easy and fast guide for the firsts steps of reversing. Obviously reverse engineering is a world and also if you play CTF this guide will not be useful for you, at lest for the normal tasks where you have to look the assembly code in functions to understand what the program is doing.Determining file typeExploring dependenciesParsing the ELF binaryDynamic …

Fixing chinese Bluetooth dongle for Linux

Most of cheap Bluetooth dongles from Aliexpress do not work natively in Linux. I have been looking the source code of Bluetooth Linux driver looking for this problem and I have found that it is because some of these dongles are blacklisted because they are using for malicious actions. Thus if you want to use one of these dongles you should remove this code which blacklists the dongle.Identifying the problemTo identified the problem I connect the device but nothing happen. …

write4 challenge of Rop Emporium

Over the past few days I have not enough time to write and play CTF games, but yesterday I had a little bit of time, so I searched a bit about websites which has challenges about exploiting, I found a lot of websites with these kind of challenges thus I chose one of them, ROP Emporium and the challenge Write4 (random).So, It is a writeup about this challenge, I have used peda and pwntools.Solution write4: ELF 64-bit LSB executable, x86-64, …

Momentos y decisiones

Existen momentos en la vida en los que hay que tomar decisiones, a veces podemos llegar a pensar que no no tenemos que elegir, y simplemente dejarsnos llevar, aunque amigos, esto también es tomar una decisión.Me estoy refiriendo a decisiones de verdad, no a la elección de que tipo de leche comprar en el supermercado, me refiero a decisiones de la vida. La vida de cualquier persona esta cambiando a cada segundo.De entre los 86400 segundos que tiene el día …