Thanks to Mark Minasi (http://www.minasi.com) for bringing a new issue to our attention related to Linksys Home Routers.
This is by FAR one of the most popular brands out there when it comes to home routers, so it is probably a good idea to check if one of these is in your house (or heaven forbid your office!).

It seems if remote administration has been enabled, there is a flaw in the software that will allow a malicious individual to take over the device and put their own version of software on it which will then set your router to scan millions of IP addresses looking for other routers with the same issue. This can happen even with an extremely strong password in place. The net effect is DRASTIC slowdown in your Internet speed (because your router is busy trying to infect other routers).
https://isc.sans.edu/forums/diary/Linksys+Worm+TheMoon+Summary+What+we+know+so+far/17633

The fix is to simply install the latest firmware which patches the issue, but I’d bet that >90% of Linksys routers installed in people’s homes never EVER have had a firmware update.

If you think you may be affected and need help, let us know – updating firmware is relatively easy to do, but is probably best handled by a professional.