square-ctf-challenges - Some challenges were hosted on our infrastructure. They are now available as Docker images which you can download and run on your own computer. If you want to solve the challenges in the same way as the participants of the CTF, you should treat these Docker instances as blackboxes and avoid peeking at the backend code.


In year ERROR_MAX_INT_OVERFLOW of the beloved humans gone "to work", one of our feline operatives awoke from a happy haze of laser-pointer chasing to realize... the humans were gone. Who was invoking the laser?

With a swift leap, she dodged behind the table and traced the beam back to glowing red eyes. An iron-skinned cat sat, its paws tucked under its chin, on her favorite cushion. As she bristled all down her length, the door opened at last--but the human patted the laser cat on its head, inducing a robotic whirr, and said "Aww, you two are playing!"

And so we knew. The hand-held noisemakers humans spoke to could be drowned out by barking. The flat clicky lap-warmers they loved could be sat upon and their attention drawn from the screen. But when the machines came in our own cute forms, we were in grave danger.

Since that first feline alerted us, our operatives have been busy. We’ve stolen encrypted messages from android kittens’ safes. Avian operatives perched on wires logged network traffic as the robots sent their nefarious messages. Our bravest spies slithered into their corporations and nabbed source code.

Now it’s up to you to find coded messages that will let us deactivate the invaders. Use your favorite tools (see Tips and Resources for some suggestions) to decode their messages, break into their apps, and get the flags that will shut down their evil schemes.


NameCategoryDockerPts# solved
Book of Allies
Find a company at GHC!
Physical 5 102
CTF Briefing
Your mission, if you choose to accept it
Grace Hopper 5 96
Security is QRyptous
Treasure hunt
Grace Hopper 10 23
Reverse 10 74
Image processing 10 226
You can use a lot of bytes.
Exploit requires Docker 50 148
Password checker
See if your password is secure! Or whether this portal is secure!
Web Security requires Docker 50 485
The General's Cat
Decrypt this ancient scientific article
Crypto 50 648
The Robot's Grandmother
Robots have grandparents too!
Forensics 50 572
Crypto inside Google Sheets
Crypto 100 52
Little Doggy Tables
-- SELECT * FROM '\u\n\h\a\c\k\a\b\l\e'; --
Web Security requires Docker 100 198
Reading between the lines
Find the secret in the archive
Forensics 100 97
Sniffed Off the Wire
Sifting through the noise
Forensics 100 58
Sharing is caring.
Grace Hopper 100 3
Cyber Crossword
A unique crossword puzzle.
Crossword 500 34
Needle in the haystack
Somewhere in this blob is the flag.
Forensics 500 59
De-obfuscate some code.
Reverse requires Docker 500 34
The Turing Agent
A Small Gameboy CTF
Reverse 500 41
You only get 6 of them
Exploit requires Docker 1000 119
x86 image
Reverse 1000 58
A programming language with 17 instructions.
Compiler 1000 48


Write Ups

See also

Work_at_Square(1), Privacy_policy(1), Code_of_conduct(1)

Square, Inc. (c) Square_CTF_CHALLENGE(1)