Hi I haven’t been blogging / working 😉 so much as I’ve been quite busy and in the process of relocating – but have decided to do this post and due my interest in networking and security I have decided to learn the basics of assembly which does seem a bit full on. However my personality is all or nothing and when learning something, I like to go in depth and really understand what I’m doing. I have been following a few tutorials from Live Overflow seen in the video below and the last one I watched has a focus on CPU and Assembly language. After watching this, I decided to learn more about Assembly as I think it will be very useful to learn considering my interests.
So during this video I learnt some fundamental concepts of Assembly however this blog post I want to write about working with memory mapping in Linux based on another Youtube tutorial seen below, this tutorial is very good and it’s what this blog post is based around:
It is important to know the basics of program memory and how it is used which can be seen in the diagram below, in this post I mainly want to talk about the address of the stack and how this can be manipulated by changing the randomize_va_space in Linux.
The .text file deals with the executable file however during this post I want to focus mainly on the stack and the address of the stack in the maps file and how we can go about viewing and changing the memory address of the stack by changing the
randomize_va_space file found in
proc/sys/kernel/randomize_va_space . We do this by modifying the contents of the file. By inserting a 0 into this file, then the stack memory address will never change. This is really insecure and can allow vulnerabilities to happen but it is useful to change it for demonstration and learning purposes.
The video below details more about ASLR in Linux and how this works. I created this video because I think quite often its easier to learn by going through something step by step and seeing it visually than reading about it, however I am planning to do another blog post more in depth on ASLR. Stay tuned and thanks for reading! 🙂