ASUS uses their own Linux distro called ASUSWRT, whenever I've looked at it it's been, well ... <i>interesting</i> from a security perspective, even compared to other WRT OSes.<p>I did a ton of stuff on the AC series and some of their smaller hardware (like the WL330-NUL which is an awesome little thing but riddled with bugs). The bottom line is that if you have an ASUS, you should expect bugs.<p>If you're worried about being exploited via your router, making sure you use a dedicated browser to configure a router and have no other web pages open at the time will help against certain classes of bug, as will logging out immediately after you've finished. Making sure that you know what's being forwarded is also useful, as is turning off UPNP.<p>OpenWRT is a little bit better (but people tend not to update their routers) but has it's flaws for various reasons (mostly in the web interface), as do most of the WRTs. If you're really worried, Mikrotiks tend to be better, and very little beats an OpenBSD firewall.