My phone is rooted and has USB debugging enabled, because I do some development on it. In a moment of pre-caffeinated mental weakness, I plugged it into a cheap Chinese power bank.
The phone promptly stopped responding to touch input until I hard-rebooted. This reminded me that malicious chargers are apparently a thing. My google-fu hasn't shown any in the wild, I have no other symptoms, and MalwareBytes is giving me the all clear... so I'm not particularly worried.
Generally speaking though, how would you go about detecting a malicious charger?