Smash the Stack IO Level 4 Writeup

Introduction

It's been a while. I suppose finals, projects, etc. will do that. Anyway, I figured it was time to get back to posting content on here as much as possible - and I have some neat projects underway that I'm excited to share soon. For now, I'll continue the previous series covering the IO wargame on smashthestack.org.

Smash the Stack IO Level 3 Writeup

Introduction

For the third level of Smash the Stack (IO), we are given both the source code and a binary to work with. As always, we will use the password obtained in the previous writeup to login to the server as 'level3'. Let's take a look and see if we can find a way to extract the password for level 4.

Smash the Stack IO Level 2 Writeup

Introduction

We can use the password found in the previous writeup to log in to the server as the 'level2' user. As always, the levels are in /levels. We can see that there are two possible levels for level2: level2, and level2_alt. For the sake of this post, I will focus on level2, but may update it with the solution for level2_alt later.

Smash the Stack IO Level 1 Writeup

Introduction

One of the best ways to either learn new exploitation techniques or practice ones you already understand is through events called Wargames, otherwise known as "Capture the Flags" (CTFs).  There are two common types of CTFs: a typical "Offensive/Defensive" strategy, in which teams are simultaneously attacking each other's networks in attempt to capture their flag, and a "Jeopardy", or "Offense Only", type in which all teams are trying to solve problems to obtain the same flag.

In addition to this, CTFs can be further classified as either 'ongoing', in which participation is not limited to a small time frame, or 'Event Based', in which participants have a limited time (usually a few days) to attempt to capture as many flags as possible. As an example, the recent CSAW CTF (for which there are writeups on this blog) is considered a Jeopardy-style Event CTF because participation was limited to a weekend.

Now, with the introduction out of the way (see the end of the post for misc. CTF resources), the following is a writeup for level 1 of the ongoing Jeopardy-style CTF called Smash the Stack - IO. I have tried to make the writeup comprehensive for those that may have never participated in a CTF, or do not have much experience reversing binaries.