On 2010 Moscow communicated with a ring of alleged spies in America by encoding instructions in otherwise innocent-looking images on public websites. It’s a process called steganography. Steganography is a smart way to hide data into other files, called carriers.
If a hacker managed to compromise a server, it can be used for several things like spreading viruses, sending spam, attacking other hosts or steeling and destroying sensitive information stored on the server. Restoring a previous copy of the system