Cracking the Code: A Deep Dive into Multi-Layer Steganography

Cracking the Code: A Deep Dive into Multi-Layer Steganography 

I just wrapped up a fascinating CTF (Capture The Flag) challenge by HIVE Consult that perfectly illustrates why you should never take a file at its face value. What looked like a standard JPEG was actually a Russian Nesting Doll of hidden data. The JPEG in question is the banner image above.

Phase 1: Metadata Mining. 
The first rule of forensics: "Open your eyes to the metadata." Using exiftool, I discovered a hidden string tucked away in the "Comment" field: c3Rle2hpZGU6cEF6endvcmV9

Phase 2: The Double Decode. 
The string was encoded in Base64. After the first decode, it revealed a hint steghide:cEF6endvcmV=, which pointed me toward the specific tool needed. A second decode of the remaining string gave me the golden ticket: the passphrase "pAzzword"

Phase 3: Pixel Extraction. 
With the password in hand, I used steghide to extract the secret payload embedded within the image’s pixels. This successfully pulled a hidden flag.txt file out of thin air. 

Phase 4: The Flag.
Reading the extracted file revealed the final objective:
picoCTF{h1dd3n_1n_1m4g3_5d4cba73}

This challenge was a great reminder that security isn't just about what you see on the surface. It’s about the layers of data hidden underneath.