Comcast Routers Learned to Spot Motion in Your Home — and to Share It

Comcast has added a new feature to its wireless routers — motion detection. The technology tracks disturbances in the Wi-Fi signal between the router and connected devices such as a TV or a printer, and sends the user push notifications when someone stirs near one of them.

In the Xfinity app you can set up different modes — for when the household is home, asleep, or away — and also view motion activity in real time along with a feed of recent events. In effect, an ordinary home internet connection is turned into a makeshift surveillance system that needs neither cameras nor dedicated sensors.

It Doesn't Always Work

Comcast is candid about the limitations. Accuracy is affected by the size and layout of the home, the wall materials, and the placement of the router and connected devices. The company makes no guarantees that it will work — so it's more of a nice bonus than a reliable security service.

The Real Problem Is in the Fine Print

Commenting on the new feature, Bruce Schneier notes that what they've built is an excellent surveillance tool. But the real alarm comes not from the technical limitations but from Comcast's own support page. It states outright that the information generated by the WiFi Motion feature may be handed to third parties without any additional notice to the user — in connection with any law enforcement investigation or proceeding, any dispute to which Comcast is a party, and pursuant to a court order or subpoena.

In other words, the data on when and where movement occurs in your home is potentially available not only to you. Commenters on the blog reacted with predictable sarcasm: providers simply cannot resist the temptation to collect absolutely every piece of information — “to improve the service,” of course.

There's also a practical tip from readers: a subscriber has the right to use their own cable modem, as long as it meets the minimum DOCSIS standard the operator requires. By getting a modem without Wi-Fi and building a chain of your own routers, you can separate the wireless part of the network from the provider's equipment — and, in the process, deny it the ability to monitor movement in your apartment.

Source: Schneier on Security