---
title: "What is BadUSB? | Daniel Christensen"
canonical_url: "https://danielchristensen.no/en/glossary/badusb"
last_updated: "2026-09-02T13:50:00.508Z"
locale: en
meta:
  description: "A USB stick that pretends to be a keyboard and types commands on your machine within seconds."
  "og:description": "A USB stick that pretends to be a keyboard and types commands on your machine within seconds."
  "og:title": "What is BadUSB?"
---

[← All terms](https://danielchristensen.no/en/glossary)Glossary

# BadUSB

A USB stick that pretends to be a keyboard and types commands on your machine within seconds.

Also called: Bad-USB, bad usb

A BadUSB looks like a perfectly ordinary flash drive, but presents itself to the computer as a keyboard. The moment it’s plugged in, it “types” commands faster than any human could: installing malware, extracting data or opening a backdoor, often without antivirus reacting.

That’s why “found a USB stick in the parking lot” is a classic in attacks against companies, and one of the demos that makes the biggest impression in my talks. The rule is simple: unknown USB devices never go into a machine you care about.

The trick is that a computer has no good way to tell a real keyboard from a fake one. When the device says it’s a keyboard, it gets treated as a keyboard, and everything it “types” is just ordinary keystrokes as far as the machine is concerned. That’s also why antivirus rarely fires: nothing suspicious happens at the moment it’s connected, it happens afterwards.

The defense is partly technical and partly practical. Many organizations block unknown USB devices in the machine itself, and small adapters exist that pass power only, for when you have to charge somewhere unfamiliar. But the most important part is that people know the stick in the parking lot isn’t a find, it’s bait. That’s usually the one sentence that sticks after the demo.

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