Consider this backdoor: - if the decompressed stream contain a magic keyword, run the rest of the file as x86-64 binary. Now you just need any opaque binary f

Consider this backdoor: - if the decompressed stream contain a magic keyword, run the rest of the file as x86-64 binary. Now you just need any opaque binary file to host the payload. A PNG works fine, because most decoder don't care extra bytes at the end.