Ultrasounds emitted by ads or JavaScript code hidden on a page accessed through the Tor Browser can deanonymize Tor users by making nearby phones or computers send identity beacons back to advertisers, data which contains sensitive information that state-sponsored actors can easily obtain via a subpoena.
This attack model was brought to light towards the end of 2016 by a team of six researchers, who presented their findings at the Black Hat Europe 2016 security conference in November and the 33rd Chaos Communication Congress held last week.
Their research focuses on the science of ultrasound cross-device tracking (uXDT), a new technology that started being deployed in modern-day advertising platforms around 2014.
uXDT relies on advertisers hiding ultrasounds in their ads. When the ad plays on a TV or radio, or some ad code runs on a mobile or computer, it emits ultrasounds that get picked up by the microphone of nearby laptops, desktops, tablets or smartphones.
These second-stage devices, who silently listen in the background, will interpret these ultrasounds, which contain hidden instructions, telling them to ping back to the advertiser's server with details about that device.
-- submitted from IRC
(Score: 2, Informative) by Anonymous Coward on Monday January 09 2017, @03:08PM
There's no technical reason why disabling javascript should result in disabling functionality. Maybe if more people disabled it, then more websites would work correctly without it, to the benefit people using TOR to avoid censorship.
Because this method can only find old threats after they have successfully attacked many people.
(Score: 0) by Anonymous Coward on Monday January 09 2017, @03:21PM
That's his point, the problem here is that advertisers feel entitled to do whatever the hell they want to track people and generally behave like amoral crackpots. You should have to disable ads in order to have a reasonably safe visit to a website. But, so many websites use ads that aren't simple GIFS and JPGs or god forbid text, that disabling them becomes more or less necessary to avoid malware.
Going online is never going to be completely safe, but it's ridiculous that advertisers seem to feel the need to spy. It's bad enough when alphabet soup agencies do it, we don't also need advertisers doing it for them.