Kitty Cats (500 pts)

Check out my collection of kitty cats – aren’t they adorable? Can you find the hidden message? It’s a two word phrase linked to these fearsome furry creatures. Answer is two words, lowercase i.e. starry night

Solution

We are given four images, each named onetiger.jpg, twotiger.jpg, threetiger.jpg, and four.jpg.

onetiger.jpg	twotiger.jpg
threetiger.jpg	four.jpg

At first, I thought that the hidden message has something to do with the tiger itself, because each photo shows a different type of tiger, which are, in the naming order of the files:

1: panthera tigris jacksoni (malayan)
2: panthera tigris altaica (siberian/amur)
3: panthera tigris sumatrae (sumatran)
4: panthera tigris tigris (bengal)

After wrapping my head around this for hours, I was stuck. The only two word phrase that connects the four tigers is panthera tigris, yet it's not the answer.

Pondering at the challenge description, "hidden message" can come from the image's content (in this case the tigers) or the image file itself (see steganography). To confirm this, take for example, onetiger.jpg. Using reverse image search, we can get the original source of the image. When checking their hash, it can be confirmed that the challenges' images has been modified from the original.

The difference is clear when we check both images' metadata using exiftool.

At this point, it's clear that the "hidden message" is located in each image's metadata, specifically in this attribute called "XP Comment", which all of the challenge images have.

Combining all of them in order, we get the base64 srtring ZmVhcmZ1bCBzeW1tZXRyeQ==, which decodes to fearful symmetry.

Flag: fearful symmetry