The main idea finding the flag is using binwalk and Stegsolve.
After I downloaded Exclusive_Santa.rar, we have 1.png & 3.png in it.
When I tried binwalk 3.png, I got other zip files in it.
So, when we extract those and then use Stegsolve with Image Combiner (basically XOR), we get the flag.
Finally the flag becomes:
CTFlearn{Santa_1s_C0ming}