By Jeremy Hsu on September 24, 2024
Popular smart TV models made by Samsung and LG can take multiple snapshots of what you are watching every second – even when they are being used as external displays for your laptop or video game console.
Smart TV manufacturers use these frequent screenshots, as well as audio recordings, in their automatic content recognition systems, which track viewing habits in order to target people with specific advertising. But researchers showed this tracking by some of the world’s most popular smart TV brands – Samsung TVs can take screenshots every 500 milliseconds and LG TVs every 10 milliseconds – can occur when people least expect it.
“When a user connects their laptop via HDMI just to browse stuff on their laptop on a bigger screen by using the TV as a ‘dumb’ display, they are unsuspecting of their activity being screenshotted,” says Yash Vekaria at the University of California, Davis. Samsung and LG did not respond to a request for comment.
Vekaria and his colleagues connected smart TVs from Samsung and LG to their own computer server. Their server, which was equipped with software for analysing network traffic, acted as a middleman to see what visual snapshots or audio data the TVs were uploading.
They found the smart TVs did not appear to upload any screenshots or audio data when streaming from Netflix or other third-party apps, mirroring YouTube content streamed on a separate phone or laptop or when sitting idle. But the smart TVs did upload snapshots when showing broadcasts from the TV antenna or content from an HDMI-connected device.
The researchers also discovered country-specific differences when users streamed the free ad-supported TV channel provided by Samsung or LG platforms. Such user activities were uploaded when the TV was operating in the US but not in the UK.
By recording user activity even when it’s coming from connected laptops, smart TVs might capture sensitive data, says Vekaria. For example, it might record if people are browsing for baby products or other personal items.
Customers can opt out of such tracking for Samsung and LG TVs. But the process requires customers to either enable or disable between six and 11 different options in the TV settings.
“This is the sort of privacy-intrusive technology that should require people to opt into sharing their data with clear language explaining exactly what they’re agreeing to, not baked into initial setup agreements that people tend to speed through,” says Thorin Klosowski at the Electronic Frontier Foundation, a digital privacy non-profit based in California.
Doesn't help if the device has a baked in DNS address and just ignores your settings tho. Amazon and Google devices seem prone to that. After blocking everything on the common DNS ports except the PiHole, some of my devices have been acting kinda sluggish.
Easy to block that - though not with pihole exclusively.
We use another tool at our network edge to block all 53/853 traffic and redirect all port 53 traffic to our internal DNS resolver (works much like pihole).
Then we also block all DoH.
Only two devices have failed using this strategy: Chromecast - which refuses to work if it can’t access googles DNS. And Philips Hue bridges. Both lie and say “internet offline”. Every other device - even some of the questionable ones on a special VLAN for devices we don’t trust - work just fine and fall back to the router-specified DNS.
I wanted to do that as well, but I can't redirect outgoing traffic on my router, just block it entirely. Sadly it was the only device of that series not supporting OpenWRT (sigh)... Next one will either have to support that or be a DIY project... Have been starting to self host my stuff already and I'm not planning to stop there!
How do you identify DoH Vs normal web traffic?
That's the problem with my router... I can't. I've seen it done with OpenWRT but I chose the wrong model for that...
I asked because I'm not sure it's really possible.
Sweet. It’s worth it IMO. And definitely fun for either tinkering or just having something solid that works (why not both? ;) ).
We’ve been using monowall - now pfsense since 2008.
I don’t necessarily recommend btw - there are lots of great options out there (like it’s cousin OPNSense and so many more).
Yeah, the tinkering is part of the fun. Right now I'm still perfecting my OMV NAS/Homelab but after that I might look into custom routers. I'm still hoping to get fibre in the foreseeable future, but right now it's not looking too good in my area...