Tool Easily Breaks Into Locked PCs

Proving once again that you can do a lot of damage with a little investment and a lot of ingenuity, security researcher Samy Kamkar recently managed to take down a locked, password-protected computer armed with only a US$5 Raspberry Pi.

The low-tech cookie-siphoning intrusion is one of Kamkar’s simplest hacks ever. He previously has unlocked car doors, garages, wireless remote cameras and other devices, with MacGyver-like precision.

Kamkar’s latest hack, PoisonTap, uses a Raspberry Pi Zero, a micro SD card, and a micro USB cable or other device that emulates USB, including USB Armory or LAN Turtle.

Windows, OS X and Linux recognize PoisonTap as an Ethernet device, load it as a low-priority network device, and perform a DHCP request across it, even if the computer is locked or password-protected, Kamkar explained.

PoisonTap provides the computer with an IP address. However, the DHCP response tells the machine that the IPv4 space is part of PoisonTap’s local network, rather than a small subnet, he said.

If a Web browser is running in the background, one of the open pages will perform an HTTP request in the background, noted Kamkar. PoisonTap responds with a spoof, returning its own address, and the HTTP request hits the PoisonTap Web server.

When the node Web server gets the request, PoisonTap’s response is interpreted as HTML or JavaScript.

The attacker is able to hijack all Internet traffic from the machine and siphon and store HTTP cookies from the Web browser or the top 1,000,000 Alexa websites.