Invisible Finger

Invisible Finger Controls Touchscreens

Invisible Finger

Imagine. You enter the meeting room, set your phone down, and sit down. An invisible finger unlocks and instals malware on a sleeping phone. Ghostbusters! Call the team whose “invisible finger” presentation impressed Black Hat conference attendees.

“Security in Silicon Lab” “University of Florida and University of New Hampshire professors, PhD candidates, and other academics with competence in electronics hardware, math, and physics.

Haoqi Shan, a UF PhD candidate, presented the group’s findings at Black Hat. This is a remote touch injection attack employing IEMI (intentional electromagnetic interference) “saying “Our assault range is 3-4cm. We can induce a tap, long-press, or swipe in any direction.”

Shan called it a “Once you have the expertise here, you should be able to recreate what we’re doing. Maybe you’ll have a better or cooler attack.”

Continuing the research would require powerful equipment, knowledge, and skill.
Shan explained how capacitive touch screens control tablets and phones. Skip the physics: An electronic system converts capacitance events into measureable voltage. Voltage is manipulated by electromagnetic fields.

Shan remarked, “That could work, but we don’t know.” “We set up an environment with a copper plate to generate a field for touch control.”

The team iterated to find the optimal field strength and frequency. Shan: “We need a focused e-field.” Two methods were employed. Spring-loaded copper needle is more accurate, but copper plate generates a stronger signal.


Shan: “You can’t use a robotic arm to attack.” “We used a sparse antenna array to locate the phone and another array to test. iPad, OnePlus, Google Pixel, Nexus, and Surface are vulnerable. Universalizes. It works like your finger. iPad and Surface support omnidirectional swipes. This might open a gesture-based lock.”

The squad planned an attack. A tabletop antenna array pinpoints the phone or tablet’s location. Touch signals come from another antenna array. The attacker system can validate each touch by measuring screen emissions. A video depicts the last onslaught.

Possible Attacks Defenses?

“We installed a malicious programme for Android,” says an actual attack scenario “said Shan. “PayPal press-and-hold sent money. We devised a Siri attack that works 9/10 times.” Other attacks were less successful, in part because Android’s Yes and No buttons are so close.

Touch-screen manufacturers might prevent this by detecting pressure or force. The invisible finger attack applies no pressure. “Consumers can use a Faraday bag, but it renders phones useless,” stated Shan. A case with a cover and Faraday cloth provided good protection.

The group’s website notes that putting your phone face-up will safeguard it from the attack.

Shan: “We’re still perfecting this attack.” He also said the group hires cybersecurity PhDs. Yes? You can contact the organisation through their Invisible Finger website, which includes FAQs, videos, and the research article on which this presentation is based.


More From Us:


Leave a Comment

Your email address will not be published.