34C3 CTF PWN LFA Write-up

Introduction

I did not take this challenge during the contest. But after reading the write-up of [1][2][3], I think it’s a good chance to learn about ruby and sandbox escape. According to my test on the local machine, it seems that using one_gadget to get shell is also feasible. In this post, I will talk about how to trigger the vulnerability and hijack control flow to get shell in the end.
Since this is my first time to write ruby script also my first time to write ruby escape, please forgive my ugly code XOrz.
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Extra Heap Exploitation: House-of-Rabbit

Introduction

In recent HITB XCTF, this technique is used in one heap challenge. I think it’s necessary to give a basic introduction on this also as an extension on my tutorial on largebin in ptmalloc.
The criteria for this exploitation technique is strict compared to other techniques and requires a lot of manual craft to assure the exploit is successful. The advantage of this technique is that the whole exploitation no longer depends on the knowledge of the base address of libc. But the advantage is limited as we still need a known address in advance, which can by repeatedly and reliably modified. Maybe the CTF community may find more potential of such technique in future.
The original information about this technique can be found in [1]. My post is based on this blog.
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