plaidCTF 2014 - ezhp (pwn200)
ezhp Pwnables (200 pts) ------------------- Luckily when you travel back in time, you still get to use all your knowledge from the present. With that knowledge in hand, breaking into this service (at 188.8.131.52:9174) owned by The Plague shouldn't be hard at all.
To set the picture, let’s identify the binary
izsh@box:~$ file ezhp ezhp: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=0x5fa5bd76db306497b549ea3b0466cd9e9afa2705, stripped izsh@box:~$ readelf -l ezhp | grep STACK GNU_STACK 0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x4
plaidCTF 2014 - tiffany (re300)
tiffany Reversing (300 pts) ------------------- We want to get access to a server used by The Plague. Maybe if you can find out what key is accepted by this binary you can find out where or when The Plague is...
Yay, a Linux x86_64 executable! Let’s run it and see what happens, because what could possibly go wrong when running a random binary off the internet?
$ ./tiffany This may take a while... ....... Please enter a string: TEST .... Sorry, wrong.
Well, that took 3 seconds to initialize and 5 seconds per input string character. Sure seems to be doing a lot of stuff. Let’s load it into IDA to get a general idea.
plaidCTF 2014 - paris (re300)
paris Reversing (300 pts) ------------------- This binary was found on some of our Windows machines. It's got The Plague written all over it. What secrets are contained inside?
We are greeted by a Windows executable. Since I hate Windows and I can’t be arsed to pull up a Windows VM and debugger, I decided to solve this one statically. Time to load it into IDA.
On Friday, the 13th of January 2012, the ACM Queue published an article by Poul-Henning Kamp entitled ‘The CRYPO-CS-SETI challenge: An Un-programmng challenge’. In this post, Kamp challenged his readers to attempt to disassemble a program for an unknown computer. In what we assume was an attempt at increased dramatic impact, he described a scenario where part of an extra-terrestrial computer is discovered, with only a memory storage device intact.
We first heard of the challenge on the morning of Saturday the 14th, and thought it sounded like fun. Within five days we had completely disassembled the program. In addition, we had accidentally identified the oh-so-terrestrial source of the code.
This is the first in a series of posts in which we’ll describe how we went about reverse-engineering the machine architecture using nothing but the binary blob and our wits.