Long story short:
1. Steghide (use Stegcracker to bruteforce the password) to reveal a text file.
2. White space steganography (an extra space at the end of the line) and convert to binary.
3. Convert binary to ASCII and win.

Original writeup (https://github.com/TheEquus/DUCTF-Writeup/blob/master/ILoveScomo/ScomoWriteup.md).