PRIVACY NIGHTMARE IN PLAIN SIGHT: WIFI CAN BE HIJACKED TO SEE PEOPLE THROUGH WALLS
- Mark Playne
- May 29
- 3 min read
VIDEO
More about Ruview here: https://www.notonthebeeb.co.uk/post/ruview-how-to-see-people-through-walls-using-wifi
But could it work? This November 2025 proves the tech to be true:
"BFId: Identity Inference Attacks Utilising Beamforming Feedback Information"
Published 19 November 2025
Computer Science, Engineering
You can download the paper below. Meanwhile, here is a summary:
Paper Summary: WiFi Identity Inference via Beamforming Feedback
This is a 2025 ACM CCS paper that investigates a privacy nightmare hiding in plain sight—your WiFi router's beamforming feedback data can be used to identify you with frightening precision, no specialised hardware required.
The Core Finding
The researchers developed BFId, the first identity inference attack using Beamforming Feedback Information (BFI)—data that WiFi access points and clients exchange unencrypted over the air to optimize signal direction. Their results are staggering:
99.5% identification accuracy across 197 participants, using off-the-shelf hardware. Why This Is Worse Than Previous Attacks
Attack Type | Barrier to Entry | Encryption |
CSI-based (older) | Requires modified firmware, specific hardware | Not broadcast |
BFI-based (this paper) | Any device within range can capture it | Unencrypted, broadcast openly |
The critical distinction: BFI is broadcast in the clear. A single malicious device sitting anywhere within WiFi range can record the beamforming feedback between the router and every legitimate client. No firmware hacks. No physical access. Just listen.
How It Works
Beamforming (introduced in WiFi 5/802.11ac) uses physical environment data to steer signals toward clients for better bandwidth
Clients send back BFI—a compressed representation of how the signal propagated through the environment
This compression actually filters out noise, potentially making BFI better than raw CSI for sensing
The authors fed this data into recurrent neural networks to classify individuals by their unique gait and body interference patterns
The Privacy Implications
This isn't theoretical lab work. The paper explicitly warns:
IEEE is standardising WiFi sensing (802.11bf) with zero privacy protections built in
BFI works across multiple perspectives, walking styles, and reduced sample rates
It scales to large populations (197 subjects is far larger than prior studies which typically used a handful)
The adversary model is terrifyingly weak: anyone with a laptop in a coffee shop, apartment building, or office can passively identify individuals moving through the space
The Real-World Threat
Think about what this means in practice. Every modern WiFi network is silently broadcasting enough data to:
Track individuals through smart buildings without their knowledge
Identify people in their own homes by a neighbour or a device on the street
Build persistent identity profiles tied to unique body-interference signatures—a biometric you cannot change
The authors frame this as "privacy risk investigation," but the subtext is clear: the infrastructure is already deployed, the data is already flowing unencrypted through the air, and the industry is actively working to standardise and expand these capabilities without any meaningful privacy safeguards.
WHAT THIS MEANS FOR US
Your WiFi router is a surveillance device that can tell who is in a room, what they're doing, and how they're moving... all from data that is deliberately left unencrypted and broadcast for anyone to harvest. The 99.5% accuracy figure should be deeply unsettling. This is not a future threat; the hardware is in your home right now.
DOWNLOAD PAPER
We published this article on this issue earlier in the month, showing how easy it is to do this: https://www.notonthebeeb.co.uk/post/wi-fi-has-major-privacy-concerns-that-will-shock-you
VIDEO- The dangers of WIFI's 2.44 GHZ
Interview by NOTB with the highly respected Dr Klinghardt
SOLUTIONS
Turn wifi off at night, at least 8 hours off reduces exposure by approx 33%
Use Ethernet cables for computers
Use an Ethernet cable for the phone
See products here: https://www.notonthebeeb.co.uk/post/earthing-the-ultimate-emf-protection
Comments