How to detect a malicious USB charger? 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?
You can't. The only real world way to detect if a charger is malicious is to plug it into a device that it could possibly infect. Yes, I'm sure with some forensics equipment you could technically check for this kind of thing, but it just isn't practical.

Instead, only charge your device with chargers you can trust. If you see a USB charging port, or any kind of device that is supposed to charge your phone and you aren't sure what the other side is connected to (such as in airports where there are USB ports) don't use it. 

It's more of a game of paranoia than detection. I wish there was a better alternative as much as you do.