Video conferencing participants with glasses have more to worry about than if their hair isn’t combed or if they have spinach stuck in their teeth. According to recently published research, they can also unwittingly disclose sensitive information displayed on their computer screens.
Boffins from the University of Michigan teamed up with their counterparts from Zhejiang University in China to determine whether wearing glasses while using a computer poses a safety risk.
Specifically, the researchers explored whether it was possible to determine what might be displayed on the screen by examining the reflections of a person’s glasses during a Zoom call or Google Meet sessions.
The researchers’ paper, titled “Private Eye: On the Limits of Screen Textual Display via Glasses Reflections in Video Conferencing,” describes how they set up a controlled laboratory experiment, which proved that it was possible to reconstruct and recognize on-screen text with over 75% accuracy when reflected in glasses a participant in the videoconference.
Of course, the effectiveness of the technique depends on a number of factors. These include the curvature of eyeglass lenses – with prescription eyewear proving to be more effective at providing useful reflection than eyewear designed to block blue light.
Also, of course, the quality of the video camera is essential.
A typical 720p webcam can, according to research, read on-screen text through reflections as small as 10mm.
As Researcher Yan Long Told The register:
“Current 720p camera attack capability often matches 50-60 pixel font sizes with average laptops.”
However, as higher resolution 4k webcams become more common, the spying technique could provide access to displayed text in smaller fonts:
“We found that future 4k cameras will be able to read most header text on almost any website and some text documents.”
But it’s not just text reflected off a screen that could be leaked by a wearer of glasses during a videoconference.
The researchers also found that the technique would reveal the websites a user is viewing – with 94% accuracy found in a test against Alexa’s 100 most popular websites.
So if you really think this might be a problem in your organization, what can you do?
Well, the researchers have an unorthodox mitigation.
They suggest Zoom users take advantage of a video filter feature (under “Background and Effects” in the video conferencing app’s settings) that can automatically adorn your face with glare-blocking cartoon sunglasses.
The likes of Skype and Google Meet don’t offer similar protection at the moment, but probably wouldn’t find it too difficult if the threat really became a concern.
While it’s easy to scoff at a subject like this, reflections have leaked information in the past with serious results.
For example, in 2019, an obsessed fan assaulted a Japanese popstar after determining where she lived by zoom in on the reflections in her eyeballs in the selfies the star posted on social media.