A lot easier than the amount of solves would tell you.

1. You're given a mjpg file. This is a "Motion JPG" file, which is just a bunch of JPG files put together and streamed at you.
2. Just run some sort of MJPG splitter (`ffmpeg -i mjpegvideo.avi -vcodec copy frame%d.jpg`)
3. Quickly analyze all the split out JPG files (`file *.jpg`; `jpeginfo *.jpg`; `<your-fave-jpg-analyzer-tool-there's-a-billion> *.jpg`.
4. Hopefully one of those tools, tells you in some way that the JPEG end tag (FFD9) is offset 1 byte less than the entire file size (suspiious!)
5. There's on the order of 10% of the split out JPG files w/ a wrong file size. Write a quick script to just take the last byte (the extra byte) of those files, and concatenate htem together.
6. End up with something like "lorem ipsum have a flag{asdadasdasda}".
7. ???
8. Collect flag

@eugenekolo
https://eugenekolo.com