Are internal components vulnerable to BadUSB? Say you have a laptop. Even if you don't use any USB devices (like mice and keyboard), if the laptop has internal components that connect through USB (like a webcam and fingerprint reader) could these have their firmware modified in order to persistently infect a machine?
BadUSB is no problem for internal devices. It is more the other way around, you should not connect external USB Devices to your computer.
BadUSB works in the way that you think a ordinary i-phone charging cable or a USB stick or most likely a manipulated smart phone to your computer. But in realty the device acts as keyboard, mouse and or network card,and therefore is able to change or exfiltrate or monitor data on your device.
I don't think someone will use BadUSB against you,but if you think you need protection one solution would to make it impossible to connect any external USB devices to you laptop.
There are software solutions which make it hard to use BadUSB. But they are not easy to implement or use and you need to know what you are doing to make them work.