BusKill, a $20 USB Dead Man’s Switch for Linux Laptop

‘BusKill‘ is a cheap kill cord Dead Man Switch to trigger the machine to self-destruct in case the laptop is stolen, it was designed by the software engineer Michael Altfield.

The idea is very simple, the BusKill cable connects a Linux laptop to the user, for example, to his belt. In case of theft, the USB cable disconnects from the laptop and triggers a udev script that executes a sequence of operations, from shutting down to completely wipe the device or delete certain sensitive data on the disk.

“Surprisingly, I couldn’t find a low-tech solution that implements a laptop kill cord, so I decided to build one myself for ~$20 and a simple udev rule.” wrote the expert in a blog post.

“We do what we can to increase our OpSec when using our laptop in public-such as using a good VPN provider, 2FA, and password database auto-fill to prevent network or shoulder-based eavesdropping,” says Altfield. “But even then, there’s always a risk that someone could just steal your laptop after you’ve authenticated!”

The expert published a video showing BusKill triggering a kill signal when the magnetic breakaway is tripped.

Altfield published the instructions to build the BusKill cables just buying a few components for a price ranging from $20 up to $45:

1. A cheap $4 USB drive with durable keyring hole
2. A small & strong carabiner keyring for attaching the above drive to your belt loop (I like this $6 one because it’s small, well-made, and has a clever locking mechanism)
3. A $7 USB magnetic breakaway adapter to plug into the computer’s USB-A port
4. And finally, a $3 1-meter USB extension cable to connect them

The expert published two sample udev scripts that lock the device by activating the screensaver and shuts down the laptop respectively.

Pierluigi Paganini

(SecurityAffairs – BusKill, hacking)

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