Banananana 🍌

Challenge Information

• Challenge Name: Banananana
• Category: Steganography
• Points: 200 pts
• Teams Solved: 11
• Description: "Obama loves banana. But the peels are scattered everywhere. Can you clean this mess and reveal what's lurking beneath all this?"
• File: banananana.wav
• Flag: EOF{hidden_among_bananananananana}

Solution Methodology

Step 1: Initial Thoughts

The word banana being repeated and the reference to peels suggested that the data might be hidden in the file's metadata or text strings rather than deep frequency analysis.

The challenge was in the Steg category, so the first step was to extract readable text.

Step 2: String Extraction

I decided to use the strings command — a simple yet effective tool to extract printable characters from binary files:

strings banananana.wav | grep EOF

This command looks for any lines containing the keyword EOF, which is often used in CTF challenges to denote hidden messages or flag formats.

Step 3: Discovery

The output revealed the following lines:

EOF_BEC
;EOF{hidden_among_bananananananana}

Clearly, the flag was right there, hidden among the extracted text — just as the challenge hinted.

Key Insights

Why This Challenge Works

• Simple steganography using embedded text in audio file
• The "peels" metaphor referred to extracting the outer layer (strings)
• No complex audio analysis needed - just text extraction
• Demonstrates that not all audio steg requires spectrograms

Tools Used

• strings - Extract printable strings from binary
• grep - Search for EOF pattern

Alternative Methods

# Method 1: View all strings
strings banananana.wav | less

# Method 2: Save strings to file
strings banananana.wav > output.txt
cat output.txt | grep "EOF"

# Method 3: Use hexdump
hexdump -C banananana.wav | grep -i "eof"

Summary Table

Step	Action	Result
1	Analyzed the .wav file	Contained hidden data
2	Used strings with grep EOF	Found embedded text
3	Extracted flag in EOF{} format	Success!