Two can play at that game. You can store data in JPEG that can even survive recompression with lower quality. If it's worth it to you to go to all that trouble, that is.
Interesting paper: Bypassing Cloud Providers’ Data Validation
to Store Arbitrary Data [1]
>JPG & PNG Steganography Encoder (JPG-PNGStega).
The purpose of this encoder is to inject data (hiding
it) in JPG and PNG files. It takes a File Format Sample (JPG
or PNG) and, for each pixel, it injects 3 bits of data in the
LSBs (Least Significant Bit). There are more sophisticated
image steganography methods already widely discussed.
However, the use of this encoder shows that even basic meth-
ods of JPG and PNG steganography are possible in SaaS
applications, and the exploitation of such method may bring
impacts
