Dressing up dogs are kinda the new thing, see if you can get this lovely girl ready for her costume party. Dog Or Frog
When we visit the page, we are greeted with a submission form. The instructions tell us that this is a machine learning problem and to not approach it as a web-exploitation problem. The goal is to submit an image that is similar (on a byte-by-byte basis) that is similar to the dog, but is recognized as a tree frog.
The final image (left) looks visually similar to the original (right), but has added noise. When submitted to the challenge site, we receive the flag: