🔴 RED PicoCTF Walkthrough🔴

🚩 Challenge Overview

• Challenge Name: RED

• Category: Forensics (Steganography)

• Difficulty: Easy (~100 points)

• File Provided: red.png (a red square image)

At first glance, it’s just a plain red PNG—but that’s usually a hint to look deeper.

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💡 Step 1: Observe & Hypothesize

The image appears uniform—no hidden text or visual cues. In forensics CTFs, this typically signals steganography or hidden metadata.

A clever hint mentioned in some write‑ups: “check whatever Facebook is called now”—Meta → pointing to metadata or hidden layers.

🔍 Step 2: Inspect Metadata (Optional)

You can inspect metadata with exiftool red.png. Though nothing crucial may pop up, it’s good habit. Let’s jump to the heavy‑hitting tool.

🛠 Step 3: Run zsteg

This tool digs out hidden data in images:

zsteg -a red.png

Look for lines like and copy the encoded string:

🧩 Step 4: Decode the Hidden Message

Grab that Base64 string and decode using online tool like : Cyberchef and you get the flag

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✅ Summary & Tips

• The blank red image is a visual clue—often used to hide info in static color channels.

• Hints like “Meta” or “LSB” are there for a reason.

• Good to know: zsteg targets PNG/BMP LSB hides, while exiftool helps with metadata.