Neurocracked CTF Part Four: The Onion Protocol

Neurocracked

From the case files of Sam Laurie

Lin’s messages stopped two days ago.

That alone would’ve been enough to worry me. But her last one didn’t just end the conversation - it detonated it.

It came through a forgotten relay node, buried deep in a deprecated meshnet.

Obsolete, officially. But someone had reactivated it. Just once.

Attached was a single line of text and an image.

The text looked like a URL - except it ended in something strange:

.onion

I didn’t recognize it at first. But after some frantic searching, I learned what it was.

A .onion address.

Part of the Tor Network - The Onion Router. Built for anonymity. Used to access hidden services that don’t exist on the surface web.

Something was wrong. Lin wasn’t just sending encrypted logs or damaged firmware anymore.

She was hiding.

And whatever she found forced her to use the darkest corner of the net to say goodbye.

The address she sent was:

http://tumf35filxbibhae4wipeetwwordf6ph6cntcpjsnc7ajxr2e2rylrqd.onion

Along with it… an image.

I froze when I saw it. Neurocracked.

Not because of what it showed, but because of how it showed it.

The symbols - arranged like a puzzle. Familiar. Angular. Ancient.

It was a Pigpen Cipher. Freemason code. The kind only used by people trying to bury secrets in plain sight.

I stayed up all night coding a Pigpen decoder.

Once I had the translation, I cross-referenced it with the .onion address, and fed both into an off-grid VPN sandbox running a hardened Tor client.

What I found wasn’t a forum. It wasn’t rebels or rogue coders.

It was a marketplace.

But not for drugs. Not for weapons.

For minds.

Welcome to Cerberus Hive

The interface was too clean. Too smooth. No broken links, no spam.

Welcome, Subscriber. Initiating Session…LICENSED ACCESS KEY ACCEPTED BrainOS™ Retainer Suite 3.5 :: Synaptic Lease Manager

Synaptic Lease.

As in: renting out your thoughts.

This wasn’t a piracy hub. This was a customer portal. For something far more organized than a hacking group.

They were running BrainOS-as-a-Service.

A black-market platform offering remote exploits for compromised brain implants.

Subscription plans let you choose your level of control:

• Tier 1: Emotional nudges.

• Tier 2: Decision overrides.

• Tier 3: Full cognitive command—with rollback.

  
  

All automated. All legal-proof. All monetized.

They called the feature: Echo Control.

And it was live.

Their FAQ bragged about 2.1 million active deployments.

I skimmed the reviews:

“Used it during my merger negotiation. Subject signed. No resistance. 10/10.”

“Tried the empathy patch trigger on a therapist. Beautiful. She cried, then forgot everything.”

They weren’t hackers.

They were venture criminals.

They'd monetized mind control like a startup.

Worse Than We Thought

Cerberus Hive wasn’t even writing the malware themselves anymore.

They’d partnered with third-party training vendors. Unsanctioned. Desperate. The kind who still had backdoor access to BrainOS™ module repositories via pirated access tokens.

Cerberus paid affiliates to embed their exploit framework into education modules.

They called it “payload-as-a-plugin.”

You embed their code in a learning module, ship it to civilians, and collect a percentage when they’re hijacked.

It was a multi-level marketing for mind control.

... and why would Lin use a Freemason cipher?

CTF CHALLENGE 004: THE MARKETPLACE

You’ve recovered the hidden .onion address to the Cerberus Hive marketplace.

Your mission: Connect to the address and find the MD5 hash flag.

You may use: Getting started with the darkweb

Pigpen Decoder

Submit your flag as:

CTF{MD5_HASH}

Neurocracked CTF Portal

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Part V