Introduction

This tutorial is part of the SecurityTube Linux Assembly Expert certification.
The goal of this assignment will be to create a Linux 32bit Shell_Bind_TCP shellcode (binds to a network port), execs a shell on incoming connection and the listening port number should be configurable.

The tutorial will contain example source with comments. Listed source code may have formatting issues so best place to obtain copies is from the projects Github repo.
Expected usage of this shellcode will be that when it’s executed on the ‘target’ system, the shell will bind to a tcp port and wait for a remote user to connect to the ‘target’ system for interaction.

Note: Example shellcode contains null characters to help simplify demonstration and processor registers have not been cleared which may lead to issues if used within an exploit.

[client]->[target host:port]

Methodology

1. Write shellcode in high level language, c.
2. Extrapolate system calls…