challenge info  
Name: Can You See Me
Category: steganography
Difficulty: Easy
Points: 100



A magician made the seven wonders disappear. But people claim they can still feel their presence in the air.

Download Attachments: havealook.jpg


First, I checked filetype using file command. Then, I used exiftool to examine the metadata, but nothing interesting was there. Next, I used binwalk to search for any embedded files, and discovered an audio file. I extracted it using the command binwalk --dd=".*".

└─$ binwalk --dd=".*" havealook.jpg 

0             0x0             JPEG image data, JFIF standard 1.01
134855        0x20EC7         Zip archive data, uncompressed size: 219888
323796        0x4F0D4         name: hereissomething.wav

The audio sounded like random noise. However, since it was a steganography challenge, I suspected that there might be a hidden message in the audio. I opened the file in Sonic Visualizer and added a spectrogram layer, which is commonly used for hiding text in audio files. To do this, go to “Pane” menu and select “Add Spectrogram”. As expected, the flag was hidden in the audio file in plaintext and became visible in the spectrogram layer.

spectrogram in sonic visualizer


Flag: VishwaCTF{n0w_y0u_533_m3}