My cat is planing something, find the hidden msg
The given file is a PDF document. binwalk reveals additional embedded data, another PDF file that contains an image of a cat. It contains hidden text with black font color on black background, CTRL+A (select all) in your PDF viewer should already reveal it, alternatively pdf2txt prints it out.
flag: SECT{3mb3dd3d_f1l3s_c0uld_b3_tr1cky}