I am currently researching techniques used to exfiltrate data, such as ICMP tunneling, SSH tunneling and DNS tunneling. I have come across the word "covert channels" but am not sure if this refers to the tunneling techniques I have mentioned. Can someone explain what the exfiltration techniques through tunneling are called? i am asking to try narrow down my research keywords. Not sure if they fall under covert channels.
Thanks in advance for your assistance