Wireless Routers as Motion Detectors

Comcast has added motion detection as a feature to its wireless routers:

The feature sends push notifications to users when motion is detected near a connected device, such as a TV or printer. It has different settings for when people are home, asleep, or away. The Xfinity app also lets users see live motion activity and a feed of recent activity.

Comcast acknowledges that the system has some limitations. Home size, layout, building materials, and the placement of the router and connected devices can all affect its ability to detect motion. Comcast says it does not guarantee its performance.

Sounds like a great surveillance tool. And also:

But the biggest privacy concern comes directly from Comcast’s own support page, which says information generated by WiFi Motion may be shared with third parties.

“Comcast may disclose information generated by your WiFi Motion to third parties without further notice to you in connection with any law enforcement investigation or proceeding, any dispute to which Comcast is a party, or pursuant to a court order or subpoena,” the page reads.

Tags: privacy, surveillance, wireless

Posted on September 2, 2026 at 6:22 AM • 9 Comments

Comments

Q • September 2, 2026 7:15 AM

information generated … may be shared with third parties.

Yup, of course. They just couldn’t help themselves. The ever present desire to collect ALL the information “to improve the service” or whatever other BS they write to fool the unwasheds into declaring it as a good thing.

TimH • September 2, 2026 7:42 AM

The good news is that customers have a right to provide and use their own cable modem, with the caveat that it has to be to the minimum DOCSIS standard that the ISP requires. Get one without wifi, and daisy chain two more routers: the first has wifi, the second the wired LAN but no wifi. Steve Gibson has an article about this https://www.grc.com/nat/nat.htm

Privacy • September 2, 2026 9:06 AM

Great, it may get used by burglars to check if anybody is home?

Ferentarius • September 2, 2026 10:42 AM

In the twilight of our supposed freedom, even the air between our walls is conscripted into surveillance. Comcast’s routers—silent sentinels of our domestic solitude—now throb with the unease of motion, whispering to unseen arbiters every tremor of our existence. A home ceases to be a sanctuary when the pulse of your steps becomes a signal, a data point to be archived, traded, or delivered under the cold eyes of profit. We have entered an age where privacy is not invaded but eroded, like a cliff face surrendering grain by grain to the relentless sea. And yet we remain, complicit and docile, marveling at the convenience of our own quiet undoing.

Clive Robinson • September 2, 2026 12:54 PM

@ TimH, All,

What Steve Gibson was describing some two decades ago was the same idea many had at the time.

The problem was it was limited in various ways (and still is) and attackers worked out ways to bypass aspects of it.

Some of us did things differently. If you look up my “Garden Path” design I add instrumentation an attacker can bot see between the two routers.

This instrumentation can then be used to “hard switch” at or before the first (WAN side) router or at or after the second (LAN side) router.

I based it on a much much earlier DMZ and Bastion Host model (so not much originality 😉 That went out of fashion when all in one “edge network devices” became popular.

The thing is “edge network devices” are almost always several steps behind not just the attackers but better defenders tools.

Worse such network routers are as we should all know by now absolutely riddled with vulnerabilities including fixed but effectively hidden passwords for admin accounts.

It’s why I recommend people build their own instrumentation from PC’s and Open Source Software.

The semi hidden trick was using a couple of “Vampire Taps” that were only RX connected thus could not be seen or enumerated by an attacker.

Importantly you had to instrument both inwards and outwards traffic. It is all to easy to miss a small new exploit trick. However a data dump being exfiltrated makes a lot of noise thus can ve used to,

“Quickly cut the wire as a precaution”

In a way it is all “common sense” but as they say,

“Common sense is oft not very common…”

Clive Robinson • September 2, 2026 1:10 PM

@ Pricacy, ALL,

With regards,

“it may get used by burglars to check if anybody is home?”

Ever thought about “Smart Infrastructure grids” being used for that?

An electricity “Smart Meter” takes measurements of electrical power consumption upto 600 times a second.

From this using simple “adaptive filter DSP” it can tell what electrically powered devices are operating.

Experiments have shown that a Flat Screen TV with a high efficiency power supply actually has a “usage signature” on the mains cable that indicates exactly what you are watching…

It has been talked about in the UK as a new way to do “TV Licencing Checks” to hit people with large fines etc.

Obviously such a system could spot you opening and closing your fridge / freezer or operating a microwave, air frier, Halogen Cooker, Induction Cooker and conventional electric oven. Or any other kitchen or bathroom gadget, including how long and how hot your shower was.

Put simply the average person can be tracked around their home just by the electricity they use. And getting at that “Smart Meter” data is way way easier than hacking a modern WiFi router to use as a form of RADAR device.

Not really anonymous • September 2, 2026 1:16 PM

You really want your own router on your side so that your ISP cannot snoop your local traffic. You also need to worry about attacks at layer 2, not just layer 3.

Gert-Jan • September 3, 2026 6:39 AM

This feature definitely adds value to people who want this.

Obviously the information is very privacy invasive. So anyone should find it completely unacceptable if any of that data would be shared without explicit permission. Such granting of permission should be optional, not prerequisite to the feature.

The other problem is that there’s no way to know if this feature is enabled without permission, if this information is accessed without permission (either by the service provider, third parties or goverment agencies), and no way to block it in any effective way, short of completely disabling WiFi.

anon • September 3, 2026 12:39 PM

Can someone say ‘oscillating fan’?

Surely this is just a more muddy extision of the research done to use wifi as radar to find people in burning buildings.

Schneier on Security

Wireless Routers as Motion Detectors

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