USB Killer: How it works and How to protect your devices

👤 Diwas Poudel    🕒 Sep 10 2021    📁 Fix    📜 0 comment

Usage of USB storage devices is massively increasing in the last few years since they are affordable and portable for everyone. So, many new computers, laptops start introducing more no. of USB ports in their system. Users of the computer do not take much attention to this port. They are widely used by attackers with malicious intentions. Attackers may just insert into a USB port and stole data, format HDD and even damage the hardware.USB Killer is one of them.

USB Killer is an electronics device that has a capacity of sending continuously high voltage into the device to which it is connected via USB Port and finally makes damages to the device. Its look and feels are like USB Flash Drive. But of easily available it is available in online market at around $3.

Purpose of USB Killer

USB Killer was initially developed for legal functions like finding out hardware vulnerabilities, test surge protection capabilities.USB Killer was initially used by Penetration Tester, Law Enforcement, Hardware Manufacturers, etc. But nowadays people are started using in an illegal way.

Who Invented USB Killer?

Actually, the inventor of the USB Killer is unknown. Some say it is invented by a Russian Computer Researcher named "Dark Purple" and some say it was by Hong Kong Based Security Team.

Different kind of USB Killers are as follow:


How USB Killer Works?

USB Killers internally consists of capacitors, resistors, diodes, transistor, oscillators, and a step-up transformer, etc. When you insert your USB drive into the USB port then the oscillator circuit of the USB Killer takes 5 V from the USB port, this 5V is input to the step-up transformer and output to 200-220 Voltage. This high voltage is provided as input to the capacitor and the capacitor charges. When the capacitor discharges, the high voltage is sent to the USB data pins and hence making damage to the motherboard as well as the PC.

If capacitors are not receiving the necessary voltage and the motherboard is not damaged then again oscillator reconnects and charging and discharging capacitors repeats with high gain voltage and discharge to USB data pins and may destroy your motherboard.

USB Killer Internal


In Laymen Term, USB Killers somehow generate 200-220 Volts internally from 5V of USB when connected to the USB port. And these 220 Volts are discharged into USB Port(which only supports 5V) and this imbalance in voltage destroys USB Port and motherboard as well.

Are USB Killers legal to Use?

USB Killers are available in the market and legally used by hardware manufacturers for testing their hardware. If you use a USB Killer for destroying another system without the permission of the owner then it becomes illegal.

All the hardware will not get destroyed by USB killer. It is said and mentions somewhere in other blogs that Apple products like MacBook Pro are not affected by USB Killer. But this doesn't mean you have to try it. If you want to do it, then do it at your own risk.

Does USB Killer destroy the hard drive?

When USB Killer is plugged into a USB port then either motherboard, USB port as well as hard drive controller might get damaged.

Does USB Killer still work?

Generally, low-end hardware devices are not protected against USB killers. Because low-end domestic devices like home PC are not mission-critical devices and saving the cost of manufacturing these devices are not protected against USB Killer.

Why USB ports are vulnerable?

USB Peripheral Devices uses USB protocol and this protocol does not have any device authentications which makes the system vulnerable so that USB Killer can easily interferer. So, manufacturers should develop a system to prevent such devices.

How to protect from USB Killer?

Some of the things you can do to prevent USB Killer are as follow :

1 Do not insert unknown USB drives in your system.

2  Always insert USB drives with a valid brand like Transcend, Scandisk, HP, Kingston, Samsung, etc.

3  Use Hyperdrive Type-C USB hubs and plug your USB flash drive into them.

Hyperdrive Type C Hub (source: amazon)

 USB Type C offers cryptographic authentication and the host system can confirm the authenticity of the USB device immediately once connection occurs so that unauthorized and inappropriate power can be detected easily and this brings difficulty for USB Killers.

5  Optocoupler circuilt may also be used as the best mitigating approach for the USB killer, It can be instaleld on a wide range of devices from PCs to mobile phones to prevent high voltage generated.

6  Last but not least, educate the people about USB killers.