|As every year hacking-lab.com carried out the annual Hacky Easter event with 27 challenges. As usual the variety of the challenges was awesome. I actually got full score this year 🙂 Many thanks to daubsi, who gave me a nudge once in a while on the last challenges (you can find his writeup here).|
I did the pwn challenge babypwn, which was really fun to do. The following article contains my writeup being divided into the following sections:
The goal of this article is to explain in detail how an off-by-one vulnerability on the heap also known as poison null byte can be exploited. Although this technique does not work with the latest libc, I think it can be used very good in order to demonstrate how exploits based on heap-metadata corruption work (also check out shellphish’s how2heap).
In order to do this I created a vulnerable program, which we will use as an example to create such an exploit. If you like to, you can start by analyzing and exploiting the program on your own (at least check out Environment):
Though it is not required to the exploit the program, the source-code might be helpful:
The article is divided into the following sections:
There were a lot of interesting-looking challenges. As always, time was the limiting factor 😉 I managed to spend 2 hours on saturday morning solving the pwn challenge babysandbox.
|As every year hacking-lab.com carried out the annual Hacky Easter event with 27 challenges. I could not spend as much time as I would have liked to on solving the challenges, but after all I managed to collect 25 of the 27 eggs and focused on this writeup.|
As the description on ctftime.org states, the ctf is primarily geared towards high school students but with a very wide range of challenge difficulty.
There have been a lot of interesting challenges which have been fun to do. I decided to make a writeup for the pwn challenge hellcode.
In the last lab we focused on Misc and Stack Cookies. In this next to last lab some characteristics when dealing with C++ are introduced.
While the last lab introduced the subject of Heap Exploitation, this lab focuses on Misc and Stack Cookies.
After we have introduced ASLR and ways to bypass it in the last writeup, we will expand our exploits to the Heap in this lab.