NAVI
In this challenge, we are given a raw audio file. We can hear the audio clearly when it is at a rate of 22050Hz. But it is like there is a voice on top of this audio. I tried different combinations and the one that fitted best our need was:
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=> Rate 48000Hz
=> Reverse the audio
I made those modifications in Audacity. For the Rate you can set it when importing the audio file as Raw or you can set it as shown below:
You have to click on the arrow at the top, select the
Rateand finally set it to48000Hz.
Now, we can like a voice but reversed. We can use the Reverse tool in the Effect tab and then heading to the Special section:
Now that we have the audio at the correct rate and reverse, we can listen to what the man says (at 2m32s):
The text is La solution est en hexadecimal 34 30 34 43 54 46 7b 31 74 72 30 5f 34 55 78 5f 52 34 64 31 30 2d 66 52 33 71 55 33 4e 63 33 35 7d
We can convert this from hex to text, and we get the flag 404CTF{1tr0_4Ux_R4d10-fR3qU3Nc35}