This article has a lot more information on the WiFi spying which is opt-in for now, but this part from Comcast’s terms of service should alarm you. And you definitely don’t want to be using your ISP’s WiFi router. And it’s looking like opensource firmware is going to be a requirement.
According to Comcast’s terms, verbatim: “Subject to applicable law, 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.” That is: law enforcement, disputes involving Comcast, subpoenas, court orders, search warrants.
https://reclaimthenet.org/no-camera-no-problem-wi-fi-can-see-you-now
Nothing about this is illegal, secret, or even particularly new, and that is sort of the problem.
By Ken Macon
On August 18, Comcast broadened the rollout of Wi-Fi Motion, a feature that turns an Xfinity Gateway into a motion detector for the home. No camera and no new hardware needed; it simply uses the Wi-Fi already in the house.
It requires an XB7 Gateway or newer, and is free and opt-in. Stationary Wi-Fi devices already in the home act as anchors; a smart speaker, a thermostat, a smart plug; customers choose which of these devices act as the anchors for detection. Comcast’s description: “Using Xfinity Gateway intelligence, WiFi Motion detects changes in the home’s radio frequency signal between the Xfinity Gateway and a Wi-Fi connected device, then sends instant notifications to customers through the Xfinity app when unexpected activity is detected.”
It works like this: A person’s body disturbs Wi-Fi signals traveling between the gateway and the devices; software reads that disturbance as movement.
This is straight from Comcast’s support language: “Motion is detected within the sensing area when movement disrupts the wireless signals that travel between your Xfinity WiFi equipment and selected WiFi-connected devices within the sensing area.” Comcast stresses that “It provides an added layer of awareness without recording video, capturing images or identifying individuals.” Also: “It is designed to detect motion, not identify specific people, and does not track the exact location of movement.”
While the alerts are meant to be useful, it’s the stored record of those alerts that raises privacy concerns. Wi-Fi Motion stores a record of motion activity for up to seven days. That rolling week of when a home is in motion maps a household’s routine: when people wake, leave, come home, when the house sits empty, when everyone is asleep. According to Comcast’s terms, verbatim: “Subject to applicable law, 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.” That is: law enforcement, disputes involving Comcast, subpoenas, court orders, search warrants.
Comcast says it does not itself monitor the motion notifications. It also cautions: “Wi-Fi Motion is not a substitute for traditional security motion detectors or video cameras. It is designed to provide awareness of motion activity within the home.” But the kind of information a seven-day movement log reveals used to require physically watching a house. Now it’s available to anyone who can get their hands on the data. It is useful to a burglar (when the house is empty), a stalker or abusive ex (when someone is home alone), and to police with a subpoena (who was home when).
Wi-Fi Motion is not new. Comcast offered it in early access in 2024. In August of that year, Xfinity customers began receiving emails announcing the feature, and they posted about it on Reddit’s r/Comcast that month. A September 2024 Hacker News thread discussed the rollout, with commenters raising surveillance concerns. Comcast rolled the feature out more broadly in July 2025; at the time, the tech press called it a potential privacy nightmare.
The August 18 relaunch folds Wi-Fi Motion into Xfinity Shield, a new home-protection bundle that also includes CyberSecure (network-level cybersecurity), Family Settings (parental controls), and Protection Modes. Packaged beside antivirus and parental controls, motion tracking arrives labelled as protection, not surveillance. The rebranding is an implicit acknowledgment that people are more likely to pay for a service that helps them feel safe than one that watches them without a clear benefit.
The research behind Wi-Fi sensing goes back more than a decade and we’ve been talking about the invasive aspects of WiFi signals for some time. In 2013, MIT’s Dina Katabi and Fadel Adib built Wi-Vi, a system that used Wi-Fi signals to see moving people through walls. A few years later, Neal Patwari, now at Washington University in St. Louis, showed that Wi-Fi signals could even detect a patient’s breathing, using a hospital bed ringed with wireless transceivers. The signals couldn’t carry actual images through the walls or the bed, but they could detect the slight changes in the wireless signal that came from a person’s chest rising and falling.
“We would be able to know pretty reliably that a person had walked by. But now, people are getting gait information — what somebody’s walking pattern is like,” Patwari says. Other researchers built a startup around using Wi-Fi to detect falls; in 2015 they demonstrated it at the White House, where a researcher deliberately tripped in front of President Obama, who called it “pretty cool.”
Over the years, the list of things that researchers have shown Wi-Fi sensing can detect keeps growing: breathing, coughing, falls, gait, heart rate, and presence, all through walls. Even when a person is in the same room as the Wi-Fi device, these signals can reveal more than you might expect. Florida State’s Jie Yang recently published work showing that people can be re-identified in new environments by their walking patterns or breathing rates.
Other teams have begun using Wi-Fi to detect falls in the elderly, to monitor babies’ breathing, or to track the movements of multiple people in a room.
Wi-Fi sensing is already a commercial industry, and it’s only just beginning. Verizon’s newer Fios routers ship with “human presence detection” built by Origin Wireless. Cognitive Systems, another Wi-Fi sensing company, says it has partnerships with more than 160 internet service providers. By one industry estimate (Cognitive Systems CEO Taj Manku), at least 30 million homes already have some form of Wi-Fi sensing available. In January 2024, Wi-Fi sensing was announced for cheap Amazon smart plugs, usable through Google, Apple and Amazon Alexa apps. Origin Wireless also sells Hex Home, small disks that track movement in a home; its CEO Spence Maid described a target use case: “I hate to even say it, but — ‘Is Mom alive?’”
Until recently, though, Wi-Fi sensing was a patchwork of proprietary add-ons and one-off features, grafted awkwardly onto a technology that was never designed for the task. That changed on September 26, 2025. The IEEE had established a task group in 2020 to standardize Wi-Fi sensing; the result was 802.11bf (“WLAN sensing”), which makes motion-and-presence sensing a defined function of Wi-Fi, so future routers and devices can do it out of the box. Origin Wireless founder Ray Liu says that with the standard in place, “It will be explosive.”
With millions of gateways already in American homes, Comcast is among the first to switch sensing on at scale — not the last. (What if someone hacks your router and uses it to spy on you, rather than the other way around?) But the trajectory is obvious: If you have a Wi-Fi connection, it will soon be watching your every move.
This may sound like the paranoid fantasy of a smart home gone wrong, but researchers have warned about exactly this trajectory. At Karlsruhe Institute of Technology in Germany, Julian Todt and Thorsten Strufe showed that Wi-Fi beamforming data plus machine learning could identify individual people walking within a network’s range with 99.5 percent accuracy, in a study of nearly 200 participants presented at ACM’s Conference on Computer and Communications Security in November 2025. “This technology turns every router into a potential means for surveillance,” Todt says. “By observing the propagation of radio waves, we can create an image of the surroundings and of persons who are present. This works in a similar way to a normal camera, the difference being that in our case, radio waves instead of light waves are used.”
On the practical risk, Todt says: “If you regularly pass by a café that operates a WiFi network, you could be identified there without noticing it and be recognized later – for example by public authorities or companies.” The Karlsruhe team urged the IEEE to build stronger privacy safeguards into 802.11bf.
“Even if your data is encrypted, somebody sitting outside of your house could get information about where people are walking inside of the house — maybe even who is doing the walking,” Patwari says. The ACLU’s Daniel Kahn Gillmor notes that, unlike cameras, Wi-Fi sensing can be more concerning “because it can be completely invisible,” and: “Just because it is a sensing mode that humans do not natively have does not mean that it can’t be invasive.”
Asked whether covert Wi-Fi tracking is happening, Jie Yang says: “It’s likely that this is already happening. That is: I don’t know that people are actually doing that. But I’m sure that we are capable of doing that.”
Comcast’s version is opt-in and stores a week of movement reachable by subpoena. What happens when this becomes the standard?