As Bleeping Computer notes, the Xfinity Shield motion detection feature is not new [0,1], and neither is the technology behind it [2]. But it seems that recent advancements in wifi-based environmental mapping via common routers has made it possible to not merely detect motion, but to identify the mass signatures of individuals with extraordinary accuracy [3,4].

> As first spotted by TechCrunch, Comcast's WiFi Motion documentation says the company may disclose information generated by the feature to third parties "without further notice to you" in connection with a law enforcement investigation or proceeding, a dispute involving Comcast, or pursuant to a court order or subpoena. [post]

Maybe someone is able to present more accurate numbers, but I see a minimum of 37,967,235 plainly labeled XFinity routers listed on Wigle [5], which could have Xtinity Shield enabled with the flip of a button. This does not include the likely millions more under unique SSIDs, or indeed any other modem which may be running a similar (but less widely accessible) wifi-based scanning technology.

That’s a lot of physical surveillance in a lot of places.

[0] https://www.reddit.com/r/Comcast/comments/1ey3m4o/new_from_x...

[1] https://cybernews.com/security/xfinity-wifi-router-motion-tr...

[2] https://www.media.mit.edu/projects/seeing-through-walls-comp...

[3] https://dl.acm.org/doi/epdf/10.1145/3719027.3765062

[4] discussion of [3] https://news.ycombinator.com/item?id=49321783

[5] https://wigle.net/stats#ssidstats