Buffer Overflow Primer Part 2 (Writing Exit Shellcode)

Welcome to Part 2 of the Buffer Overflow Primer. If you have not already done so, please start this series by viewing Part 1. The Buffer Overflow Primer requires that you know at least some basic Assembly Language. I have created a series of Assembly Language video tutorials for Hackers here, for those not familiar with the language.

In this video we will look at how to create Shellcode which we can use as payload while exploiting a buffer overflow vulnerability. Shellcode is nothing but machine code which the CPU can execute directly without requiring any further assembling, compilation or linking. Thus instructions in the Shellcode will be executed as-is. We will look at the exit() syscall and see how we can convert the assembly language code for invoking it into shellcode. In the process, we will be using the Objdump utility which ships with the Binary utils package. After you have gone through this video, you will be able to convert almost any assembly code into it's shellcode equivalent.

Vivek Ramachandran is a security evangelist and has been working in computer security related fields for the past 7 years. In 2007, Vivek spoke at world renowned conferences Defcon (WEP Cloaking Exposed) and Toorcon (The Caffe Latte Attack). The discovery of the Caffe Latte Attack was covered by CBS5 news, BBC online, Network World etc news agencies.In 2006, Vivek was announced as one of winners of the Microsoft Security Shootout contest held in India among 65,000 participants. He has also been a recipient of a Team Achievement at Cisco Systems for his work on 802.1x and Port Security modules on the Catalyst 6500 switches. Currently he spends all of his time maintaining Security- Freak.Net , SecurityTube.Net and is the co-founder of Axonize. Vivek, is a Bachelor in Electronics and Communications Engineering from the prestigious Indian Institute of Technology, Guwahati.You can contact him at vivek[at]securitytube.net