My reading of Krebs On Security (krebsonsecurity.com), Mirai scans for factory default passwords or hardcoded default admin credentials. Going at this as a non-technical person, I would:
* Inventory all IOT devices in your possession.
* Find the device manuals and make sure you've changed the default password(s). Note there may be devices where it appears you've updated, but that have secret credentials you can't modify.
* Make note of which of your devices do not have an obvious way to change the factory default password.
* Inventory all IOT devices in your possession.
* Find the device manuals and make sure you've changed the default password(s). Note there may be devices where it appears you've updated, but that have secret credentials you can't modify.
* Make note of which of your devices do not have an obvious way to change the factory default password.
* Keep an eye out for lists of devices that are known problems, here is one such sample list: https://blog.sucuri.net/2016/09/iot-home-router-botnet-lever...
* Check each manufacturer to see if they have issued a firmware upgrade to address security issues. Apply update.
* Think about retiring devices that appear on the "bad" hardware lists or the devices with unchangeable factory defaults.
Hope this helps.