Introduction
I recently had the opportunity to compete in the CSAW CTF Finals with the UMBC Cyber Dawgs. It was an amazing competition; the organizers were awesome and did a great job. We placed 7th in North America, by the way :)
If you’ve never heard of CSAW before, it’s a huge student-run security conference/competition. We played in the CTF, or capture-the-flag competition. I would consider one of the best undergraduate-level CTF competitions. CSAW CTF is a jeopardy style competition in which you have a board of challenges, and you get points for solving them. You solve the challenge by hacking at it until it gives you a flag of the form flag{th1s_i5_a_f1@g}
, which you enter into the scoreboard to receive points. Team with the most points wins.
I’ll be publishing a couple writeups about how we solved some of the challenges; this is the first one.
Challenge
We developed a much better alternative to AWS. Our high-performance kernel
driver gives us unparalleled speed of execution. And we're super-secure!
http://web.chal.csaw.io:6001/
NOTE: Login with your CTFd credentials.
NOTE: This might take a minute to start up the first time you login. Please be
patient!
NOTE: There may be ways to poke at other teams' boxes. Don't do that, it is not
part of the challenge.
NOTE: If you have issues with your instance, try logging out of the KWS
interface, and logging back in.
NOTE: Sorry for all of the notes :P
Author: itszn, Ret2 Systems
Solution
We begin by visiting the provided URL and we’re greeted with a dashboard. We have 1 KWS "instance" (lol), and we have the ability to store new JSON objects by name. So we have a key-value store of some sort.
We do some inspection of traffic (I use the Firefox DevTools), and we can see some requests to the API, and we see some requests to http://some.ip.ip.ip/action. We notice they are all POST requests, and they have a JSON payload of the form
Continue reading “CSAW CTF Finals 2017 – KWS 1 Writeup” →