There is botnet software that can infect embedded devices running Linux such as modems, routers, PVR set top boxes etc with world accessible telnet ports and default login credentials. It might not really matter if the infection is only in the devices RAM, if the device gets rebooted, but there's still an easy way in, it'll just get re-infected a short time later.
I also forgot to ask earlier - can the Asus show the IP addresses of where this traffic (if it really exists) is going?