What is USB HID

USB

Universal Serial Bus (USB) is a cable, connector, and protocol standard. USB 1.0 came out in 1996. You can read more about USB and its history on Wikipedia: https://en.wikipedia.org/wiki/USB

USB Connectors

There are plenty of USB connectors. USB-A might still be the most common one, but it is being replaced by USB type C. For using USB version 3.2 and newer, a USB-C connector is required. Another notable difference is that USB-C supports USB Power Delivery (USB-PD), which allows for higher power transfer over USB (typically for quick charging).

Source: “Connector type quick reference”, Wikipedia (CC BY-SA 4.0).

USB Device Classes

Every device falls into one of the USB devices classes defined in the USB standard. This allows the computer (USB host) to differentiate and communicate with each type of device accordingly.

source: “Device classes”, Wikipedia (CC BY-SA 4.0).

HID

Human Interface Device (HID) is one of many USB device classes. It is primarily used for keyboards, mice, and game controllers. Human interface devices are tools we use to interact with the computer. Without them, we wouldn’t have any way of using the computer! This is why USB HIDs are such an essential part of the USB standard. Almost every USB host supports them plug and play.

We will focus on USB HID for attacks in this course

Ben Eater’s “How does a USB keyboard work?”

I found this video very useful for getting a deeper understanding of the USB HID protocol and wanted to share it with you. It explains how a USB keyboard works and how it’s different from the older PS/2 connections.