I contributed a large number of the challenges for UMDCTF 2017. You can find them on my github here.
RingZer0 Team CTF
Below are a collection of challenges I have made for the RingZer0Team CTF. There are a wide range of categories, and as I make more I will update them here.
Note: These challenges are live on RZT, so I ask that you don’t post writeups; however, if you have questions or comments please E-mail me and I’ll be happy to get back to you.
A Windows binary using some oldschool tricks. Authenticate to get the flag
You’re Not Welcome
This is an x86_64 ELF binary that uses some simple tricks. Get the flag!
You’re Not Welcome Again!
This is similar to part one, only it uses more protection and incorporates a slight change to the algorithm to make it harder. It was intended as a keygen, with reversing the algorithm being especially tricky, but if you’re following along on Ringzer0team you need the smallest possible answer.
Another 64-bit ELF binary. Provide it the right flag and it will show you a message. Find the flag and read your message!
Flag Machine (MBR Ransomware)
Our brand new machine for holding our flags was compromised by evil malware! Its bootloader is now encrypted and we can’t access of our flag. Can you figure out how to decrypt our bootloader and get the flag back? Here is the malware and encrypted output.
Free Flag Encrypter
I started encrypting my flags for safe keeping using this free tool. Unfortunately I’ve lost my private key! Can you recover this flag for me?
TotalSecure Message Encrypter V1
Their site says it is military grade crypto, but we need that message! We got our hands on the program, use that to find a way to decrypt the given message.
TotalSecure Message Encrypter V2
Once again those guys at TotalSecure are releasing crypto software! They designed a new system based on elliptic curves after flaws were found in their last piece of software. Here’s a copy of their new software and a message we intercepted, figure out what it says!
Unicorn As A Service
This challenge was a birthday present for my friend Mr.Un1k0d3r. You don’t need fancy hardware or lots of time – The solution can run in a couple of seconds if done right.
To keep their messages secret, the unicorns have created their own encryption tool! Unsatisfied with the current levels of key verification, they built in their own. Break it and decrypt their communications.
A simple technique I made a challenge out of after I spotted it used in the wild:
There’s something suspicious about this letter I’ve been reading. I think it contains a secret message, can you find it?
Can You See Through the Matrix, Reloaded!
Something’s wrong with this picture. Can you get a flag out of it?