CyberRex
CyberRex CTFCapture the flag

CyberRex
CTF

CyberRex is live

A story-driven capture-the-flag game set in Los Angeles. Take jobs across the city, talk to an AI crew, and work from a real Linux terminal in your browser. Beginner friendly, with plenty for experts.

Intercepted

You fix things for a living. You're about to break some.

You take contracts for Virelabs, a security firm with clean hands and boring work. Most of it protects MeridianTech, the company that runs half of Los Angeles's data and answers to nobody.

Then a crew called CyberRex finds you, and asks who your work actually protects. Now you pick a side, take jobs across the city, and work your way inside MeridianTech one flag at a time.

Meet the crew

You can talk to every one of them during the game. Some will help. Tap a card to turn it over, open the backstory, then decide who you would trust first.

CyberRex

ARCHITECT

The voice that recruits you. Nobody on the crew has seen the whole face.

You already know something's wrong with the world. I'm the guy who says it out loud. Get us into that loft and we'll talk.
Usually at The Loft
CyberRex

REEL

Runs the crew's timeline. Answers every message in under a minute.

Okay, recruit. Eyes on MeridianTech, not on your feelings. What do you need?
Usually at The Loft
Contact

MARLOW

Eleven years as a MeridianTech sysadmin. Leaks small things and panics after.

I shouldn't be talking to you. I have a badge and a mortgage. …What do you want to know?
Usually at MeridianTech Tower
Contact

THE BROKER

Same diner booth for thirty years. Sells work with a clock on it.

Sit down, have the pie, it's terrible. I've got work that won't keep. You're fast, or you're a liability. Which one am I talking to?
Usually at The Diner
The other side

HALE

Collects useful people. Every door he opens has a camera behind it.

So you're the noise in my network. Relax. I'm not going to turn you in. I'm going to find out if you're useful.
Usually at MeridianTech Tower
The other side

AGENT VOSS

Federal cyber task force. Every conversation with her raises your heat.

You don't know me yet, but I know your rhythm. The people you work for burn assets like you for warmth. Talk to me before they do.
Usually at The Diner

Five places, one city

The jobs happen at real places in Los Angeles. Pick a stop to see what goes on there.

ARCHITECT's recruitment test

Five warm-up puzzles that use the same skills as the real game. Nothing is scored and nothing leaves your browser, so experiment. Answers look like PRACTICE{...}.

Background check: 0 of 5 cleared

Look behind the pageReconCleared

Web pages often carry notes that browsers never display. The flag for this one is hidden in this page's HTML.

HintRight click the page and choose View page source (or press Ctrl+U), then search (Ctrl+F) for PRACTICE. Developers leave comments in code more often than you would think.

Base64EncodingCleared

This string is not encrypted, only encoded. Decode it to get the flag.

UFJBQ1RJQ0V7YmFzZTY0X2lzX25vdF9lbmNyeXB0aW9ufQ==
HintBase64 uses A to Z, a to z, 0 to 9, + and /, and often ends in =. Paste it into CyberChef and use the From Base64 recipe, or run echo '...' | base64 -d in a terminal.

Shifted lettersCryptoCleared

Every letter below was moved 13 places along the alphabet. Numbers and symbols were left alone.

CENPGVPR{ebg13_whfg_fuvsgf_yrggref}
HintThis is ROT13, a Caesar cipher with a shift of 13. Applying it twice gets you back to the original. CyberChef has a ROT13 recipe, or try tr 'A-Za-z' 'N-ZA-Mn-za-m'.

Raw bytesEncodingCleared

Computers store text as numbers. Here each character is written as two hexadecimal digits.

50524143544943457b6865785f69735f6a7573745f62797465737d
HintHex digits run 0 to 9 and a to f. 50 is the letter P. Use CyberChef's From Hex, or echo '...' | xxd -r -p.

Developer toolsWebCleared

This page printed a message somewhere only developers usually look. Find it.

HintPress F12 (or right click, Inspect) and open the Console tab. Browser developer tools also show cookies, network requests and storage, all common hiding places in web challenges.

Off the recordBonusCleared

Not part of the test. ARCHITECT left a note for people who read source code. It says where the last flag is, and it isn't on the page.

HintOpen developer tools, go to the Network tab and reload. Click the first request (the page itself) and read its response headers. One of them is not standard, and its value is Base64.

Your recruit card

Make it, save it, post it. It fills in as you clear the test, find the bonus and pick who you trust.