SQUID GAME — BTLO Walkthrough

Introduction

This article serves as a documentation walkthrough for the SQUID GAME lab challenge from BTLO, categorized as Medium difficulty. This lab is a CTF-style challenge where we solve various puzzles to uncover the answers to the given questions.

Unlike previous walkthroughs, I will not be providing direct answers. Instead, I’ll offer hints and guidance to help you navigate through the challenges. After all, the thrill is in the hunt!

Scenario

The lab scenario is brief and mysterious, setting the tone for the challenge:

“Will you survive the Squid Games?”

As the name suggests, we’re diving into a Squid Game-themed investigation. It’s going to be exciting and challenging. Let’s begin!

Challenge Questions

Question 1

Question:

What is the phone number on the invitation card in Squid Game?

Hint: A simple Google search for “Squid Game invitation card phone number” will reveal the answer.

Answer: *******6

Question 2

Question:

Can you extract something from the invitation card file? What is the name of the file?

Hint: After extracting the provided ZIP file, you’ll find Invitation-Card.jpg. Notice the file size—it seems unusually large. This is a clue! Use steghide to extract hidden content from the image. You'll need a passphrase (hint: think about the phone number from Question 1). Once extracted, you'll find an image of a Korean candy called Dalgona.

Answer: ******a.**g

Question 3

Question:

What hint text can be discovered in the final file?

Hint: The Dalgona image also contains hidden text, but it’s not visible normally. You need to manipulate the colors to reveal the hidden message. Use stegsolve.jar to analyze the image and uncover the text.

Answer: **d ***l

Question 4

Question:

What is the final flag?

Hint: This is the climax of the challenge! Once you’ve successfully completed the previous steps, examine the Dalgona image carefully. Pay attention to the right side of the image — you’ll notice a line next to the island. To analyze it further, use this tool: https://pixspy.com/

Quick Tips for Using PixSpy:

1. Upload the image to the website.
2. Set the format to $r, $g, $b.
3. Click on the vertical line you found, from top to bottom.
4. Extract the $r values and decode the message.

This will reveal the final flag.

Answer: **T{***3_*****r_***5}

Summary of Hints

1. Phone number — Google Search: “Squid Game invitation card phone number”
2. Extracted file name — Use steghide with phone number as passphrase
3. Hidden text — Use stegsolve.jar to manipulate colors
4. Final flag — Use pixspy.com to analyze RGB values of a vertical line

Tools Used

• Steghide — Extracting hidden files from images
• Stegsolve.jar — Analyzing image color channels
• PixSpy — RGB value analysis (https://pixspy.com/)

Key Takeaways

• Steganography hides secrets in plain sight — Images can contain hidden files and messages.
• File size anomalies are clues — An unusually large image file often indicates hidden content.
• Color manipulation reveals hidden text — Tools like stegsolve can expose messages embedded in image channels.
• RGB analysis is powerful — Extracting specific color values can reveal encoded data.
• Squid Game-themed challenges are creative — CTFs often use pop culture themes to make learning fun and engaging.