RCTF 2017 - intoU - Misc

Informations

Version

By Version Comment
noraj 1.0 Creation

CTF

Description

I'm so into you I can barely breath.And all I wanna do is to fall in deep

https://static2017.teamrois.cn/misc_745cfbae1f7e94f0a49e9f81a69d72e4/intoU_71725c59e10e615f74d3ba94af441f5c.zip

For this challenge we have a wav file Ariana Grande - Into You (Samurah & DVZE Remix).wav. I didn't listen to it so I can't tell you how the music feels but I can tell you this must be a steganography challenge.

So using Audacity to visualize the file, I switched from Waveform to Spectrogram. There I went to the end of the file an see something unusual: there is a blank cut and then something that doesn't look like music.

Let's zoom.

We are able to read somethind ending with _wav, this must be part of the flag.

Now let's change some spectrogram settings.

  • Scale: Linear => Mel
  • Maximum frequency: 8000 Hz => 22050 Hz
  • Window size: 256 => 2048
  • Check Show the spectrum using grayscale colors

This is much readable now:

Flag is: RCTF{bmp_file_in_wav}.

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