I recently saw this article of a version of Mirai being spread to Android based devices via ADB enabled. My question relates to how Mirai does scanning.
Lets assume I have a Android based device (like tablet or smart TV) in my home behind a router. If a Mirai bot sends a TCP SYN to some port (like 5555 for ADB) to my router's public IP, assuming there is no port forwarding already on the router for 5555 (which is possible for most people): (1) can that TCP packet even reach devices inside the house ? (2) Does this also mean people using devices behind router don't have to worry about their devices being infected with Mirai ? (3) Is there any way attacker can overcome this situation to reach the device behind the router ?