Random Gibberish

Challenge Information

• Name: Random Gibberish
• Category: Misc, Crypto, Steganography
• Points: 200
• Teams Solved: 8
• Flag: EOF{@stley}

Solution Overview

Step 1: Initial File Analysis

# Check the file size
cat NGFYU.txt | wc -l
# Output: 9168 lines

# Check the end of the file
tail -n 20 NGFYU.txt

Result: File contains what appears to be "Never Gonna Give You Up" lyrics repeated in various orders.

Step 2: Discovery of Hidden Links

Found special lines in the file containing base64 encoded strings:

# Line 509 contained a base64 encoded string
echo "aHR0cHM6Ly9uZXZlci1nb25uYS1may15b3UtdXAudmVyY2VsLmFwcC8=" | base64 -d
# Output: https://never-gonna-fk-you-up.vercel.app/

Step 3: NGFYU Esoteric Language Discovery

The URL led to an esoteric programming language called "NGFYU" (Never Gonna F*** You Up):

• An esoteric language based on "Never Gonna Give You Up" lyrics
• Has an online interpreter at the discovered URL
• The entire file was written in this language!

Step 4: Google Drive Link Discovery

Another line contained a Google Drive link:

# Line 1751 had another base64 string
echo "aHR0cHM6Ly9kcml2ZS5nb29nbGUuY29tL2ZpbGUvZC8xVElyZGlpemFsRUdwTlU1YjRGUTlrMlhMUjRKc08xenAvdmlldz91c3A9c2hhcmluZw==" | base64 -d
# Output: https://drive.google.com/file/d/1TIrdiizalEGpNU5b4FQ9k2XLR4JsO1zp/view?usp=sharing

Step 5: Download and Analyze the Flag Image

# Download from Google Drive
FILE_ID="1TIrdiizalEGpNU5b4FQ9k2XLR4JsO1zp"
curl -L "https://drive.google.com/uc?export=download&id=${FILE_ID}" -o flag.png

# Check file type
file flag.png
# Output: PNG image (82K)

Step 6: Image Manipulation - Brightness & Contrast Adjustment

The Key Discovery: The flag is hidden in the image but not visible with normal settings. You need to adjust brightness and contrast to reveal it!

Method 1: Using GIMP or Photoshop

• Open flag.png in GIMP or Photoshop
• Navigate to: Colors → Brightness-Contrast (GIMP) or Image → Adjustments → Brightness/Contrast (Photoshop)
• Increase brightness and contrast to maximum or adjust until text becomes visible
• The flag EOF{@stley} becomes visible!

Method 2: Using ImageMagick (CLI)

# Adjust brightness and contrast
convert flag.png -brightness-contrast 50x50 flag_adjusted.png

# Or use auto-level for automatic adjustment
convert flag.png -auto-level flag_adjusted.png

# View the adjusted image
open flag_adjusted.png

Key Insights

What is NGFYU Language?

• NGFYU (Never Gonna F*** You Up) is a custom esoteric programming language
• Uses phrases from "Never Gonna Give You Up" as programming instructions
• The interpreter is hosted at: https://never-gonna-fk-you-up.vercel.app/
• The entire challenge file is a valid NGFYU program

Hidden Information

The file contained hidden metadata on specific lines:

• Line 509: Base64 encoded URL to the NGFYU interpreter
• Line 1751: Base64 encoded Google Drive link to flag.png

Multi-Stage Challenge

1. Recognize it's an esoteric language (not steganography initially)
2. Find the hidden interpreter URL (base64 on line 509)
3. Find the hidden Google Drive link (base64 on line 1751)
4. Download the flag image from Google Drive
5. Adjust brightness/contrast to reveal the hidden flag
6. Extract the flag: EOF{@stley}

Why Brightness/Contrast Was Key

• The flag was written in very light/low-contrast text on the image
• Nearly invisible to the naked eye without adjustment
• Common steganography technique: hiding in plain sight with low visibility
• Could also be revealed by inverting colors or adjusting levels