The number of tools that nefarious hackers have at their disposal these days is positively frightening. Attacks seem to be growing more complex and more dangerous by the day, and we constantly see new stories emerge that cause us to rethink our own security practices. But as we are reminded constantly, it doesn’t always take complex machinery or even any real coding know-how to steal things using technology — in fact, people were recently caught using an iPod nano and a piece of plastic to steal cash from ATMs.

Now, it looks like anyone can spy on others in the vicinity with a new gadget that is cheap, relatively easy to build, and looks just like a normal cell phone charger.

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First, a disclaimer: we do not recommend building or using this device, or any other device like it. With that out of the way, a recent post on Applied Hacking is a shocking reminder of just how vulnerable we really are on our computers.

Even now, with constant reminders of how important PC security really is, new hacks will always pop up that we’re not prepared for. Such is the case with KeySweeper, a DIY device that looks like a harmless smartphone charger.

In reality, however, the device is anything but harmless.

KeySweeper is an Arduino-based device that is capable of capturing every single keystroke typed on a wireless Microsoft keyboard and transmitting them back to a host. The device can even send SMS alerts that are triggered when it records certain keywords being typed.

“KeySweeper is a stealthy Arduino-based device, camouflaged as a functioning USB wall charger, that wirelessly and passively sniffs, decrypts, logs and reports back (over GSM) all keystrokes from any Microsoft wireless keyboard in the vicinity,” Applied Hacking’s Samy Kamkar wrote.

He continued, “All keystrokes are logged online and locally. SMS alerts are sent upon trigger words, usernames or URLs, exposing passwords. If unplugged, KeySweeper continues to operate using its internal battery and auto-recharges upon repowering. A web based tool allows live keystroke monitoring.”

Building the device can cost as little as $10 or as much as $80 depending on the desired functionality, and complete instructions are available for free on the Applied Hacking website. Again, we advise against building this device or using anything like it.

A 28-minute video detailing the KeySweeper is embedded below.