Remotely Controlling Touchscreens
Researchers have demonstrated controlling touchscreens at a distance, at least in a laboratory setting:
The core idea is to take advantage of the electromagnetic signals to execute basic touch events such as taps and swipes into targeted locations of the touchscreen with the goal of taking over remote control and manipulating the underlying device.
The attack, which works from a distance of up to 40mm, hinges on the fact that capacitive touchscreens are sensitive to EMI, leveraging it to inject electromagnetic signals into transparent electrodes that are built into the touchscreen so as to register them as touch events.
The experimental setup involves an electrostatic gun to generate a strong pulse signal that’s then sent to an antenna to transmit an electromagnetic field to the phone’s touchscreen, thereby causing the electrodes which act as antennas themselves to pick up the EMI.
Paper: “GhostTouch: Targeted Attacks on Touchscreens without Physical Touch“:
Abstract: Capacitive touchscreens have become the primary human-machine interface for personal devices such as smartphones and tablets. In this paper, we present GhostTouch, the first active contactless attack against capacitive touchscreens. GhostTouch uses electromagnetic interference (EMI) to inject fake touch points into a touchscreen without the need to physically touch it. By tuning the parameters of the electromagnetic signal and adjusting the antenna, we can inject two types of basic touch events, taps and swipes, into targeted locations of the touchscreen and control them to manipulate the underlying device. We successfully launch the GhostTouch attacks on nine smartphone models. We can inject targeted taps continuously with a standard deviation of as low as 14.6 x 19.2 pixels from the target area, a delay of less than 0.5s and a distance of up to 40mm. We show the real-world impact of the GhostTouch attacks in a few proof-of-concept scenarios, including answering an eavesdropping phone call, pressing the button, swiping up to unlock, and entering a password. Finally, we discuss potential hardware and software countermeasures to mitigate the attack.
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TimH • June 2, 2022 4:39 PM
40mm… so you have to brush up to someone whose phone’s front is facing out and not moving for 0.5s.
Let me not get paranoid quite yet.