Bad Apple Writeup (dCTF 2021)
Type: Misc
Difficulty: Medium
Prompt:
Solution
We have a video(.mp4), hearing the full length reveals some weird noises in the middle. The first tool for investigating these noises is Sonic Visualizer but it can’t be directly used for mp4 files.
First we convert the video to mp3 and then open the song in Sonic Visualizer.
Navigate to the part of song which had weird noises and add the spectrogram.
This looks like a QR code but can’t be scanned directly. Adjust the scales a little (with the knobs at the bottom-right corner of workarea). Change the color and adjust the contrast a little.
The final QR code should looked like this.
Got the flag after scanning this!
dctf{sp3ctr0gr4msAreCo0l}