How can you tell your miner has been compromised other than observing that your miner configuration changes to something foreign?
Nothing else except for the obvious pool results, if your miner is compromised then your daily/weekly average hashrate will be less than that reported on the miner, there are of course other things that might cause this issue to happen such as bad internet connection, overclocking that causes hardware errors and so, but aside from that i am not aware of any other method.
well you can also monitor your network traffic and look for any unknown packet transfer, but if happens that you and the hacker use the same pool, then that would be useless.
as for the firmware, you should never use any firmware that does not come from the manufacturer, open-source firmware such Braiins might be of an exception.
