(You) may remember the old method of embedding .rar files into images and posting them on 4chan. It became ineffective once they began checking for embedded files. However, it seems like there are ways to do it much more stealthily. https://stylesuxx.github.io/steganography/ https://github.com/stylesuxx/steganography It could be very simple to use a similar technique for arbitrary binary data from any file. And perhaps the host would respond by checking for coherent files within the image, but with a non-trivial steganographic method, say one that depends on a password or seed to map the encoded pixel locations, it could be very hard to detect. Any thoughts?