Aperi’CTF 2019 - The image speaks for itself
Challenge details
| Event | Challenge | Category | Points | Solves |
|---|---|---|---|---|
| Aperi’CTF 2019 | The image speaks for itself | Steganography | 100 | 10 |
Trouvez le flag. Ici c’est relativement simple: l’image par d’elle même.
Challenge: the_image_speaks_for_itself.bmp - md5sum: 52417e96e7ebadbe0959990f35d28714
TL;DR
Open BMP as raw in Audacity an play the sound to have the flag.
Methodology
Understand the hints
In this challenge we got two hints:
- The name of the challenge which says “speaks”
- The visual content of the BMP file which is a music controller.
The hints converge towards a sound file.
Play
First thing I did was trying to open the BMP file with Audacity (drag and drop). I got the following error:
The error suggests to import the file as raw: “Importer Raw”.
I imported the file as the following: File > Import > Import Raw
The speech is a bit too fast, lets slow it down (Effects > Change speed):
Let’s play it:
Bravo, le flag est APRK{BMP_PCM_POLYGLOT}, le tout en majuscule.
For more information, the challenge has been created using this post.
Flag
APRK{BMP_PCM_POLYGLOT}