CTF Writeup — pingCTF 2021 — Steganography

Hi All,

I was wondering whether to write this article for a while. Why? Because it’s from almost two years ago and in general it’s quite easy (if you know what is going on). Moreover, this time I don’t have to many resources for you…

But, I decided to show you this Challenge, because it’s quite interesting and can be in different forms (keypoint). So I hope it will be useful for you at all. 🎉

First, please keep in mind that there wasn’t any info about keyword here — Steganography. Next, the task/challenge is from pingCTF 2021 (2021-12–19), online form. More info: https://ctftime.org/team/147266/ and https://ctf.knping.pl/ctf

Challenge name: Colors

Description is like here:

pingCTF 2021 — Colors, source: https://ctf.knping.pl/ctf

So, how to say, not so many tips:D but we can see that we have to download some .bmp file. Then, analyze it. ✨

Quick intro: “The BMP file format or bitmap, is a raster graphics image file format used to store bitmap digital images (…)”, source: https://en.wikipedia.org/wiki/BMP_file_format

But, what is ‘Steganography’?

is the practice of representing information within another message or physical object, in such a manner that the presence of the information is not evident to human…