The challenge name gives a hint about LSB. Analyzing the bit planes using [Steganabara](https://github.com/quangntenemy/Steganabara) or [StegSolve](http://www.caesum.com/handbook/stego.htm), it's easy to see the distortion, which means there is a high chance that LSB steganography is involved.

The flag can be extracted from the LSB in BGR order: