Written by Emily Leng, Writeup by MegaAbsol
Here's something a bit harder.
Is this jpg really a jpg?
Since this seems to be a steg problem, we open it in a hex editor. I used HxD. Scroll to the bottom of the file, and we see lots of "not suspicious" strings, as well as PK's (50 4B). PK is a zip file. We find the first instance of "PK" in the plaintext, and copy everything from there. We take the copied text and make it into a zip file. Looking into our new zip file, we see a "not suspicious" folder filled with .SHORT.OUT files, from 1-25. There also is a "whatAFineKeyThisIs" file. This seems like something, so we look into it.
In this file, it says:
my favorite numbers are seven and three.
gaf cnrvp qnjkfs hz zfufqgffq
The bottom seems suspicious, and looks like some kind of cipher. Plugging it into quipqiup, we get:
the lucky number is seventeen
We then look into file 17. It seems like a bunch of meaningless text, but when we CTRL+F "answer," we find:
ANSWER4Y0UREFF0RTSISC1PH3RSANDKRYPT0
C1PH3RSANDKRYPT0