Theft of Wi-Fi enabled laptops

  Riverboy 11:30 29 Jul 2005

Epsom police have issued the following notice to our local Neighbourhood Watch scheme:

"Laptops are being accurately targeted for theft by thieves using WI-FI (Bluetooth) hotspot finders. This handheld device displays the signal strength using a principle not dissimilar to metal detectors.

It enables a thief to walk into a full car park of cars and accurately select those vehicles which contain laptops. They then force entry to the vehicle and steal the laptop.

Laptops which are WI-FI enabled emit a signal even when they are hidden within vehicles and turned off. If you need to travel with your laptop, you are advised to keep it with you at all times."

Is the above at all realistic? Is it really possible for a Wi-Fi enabled laptop to emit a signal when it is switched off? How?

  Belatucadrus 14:31 29 Jul 2005

Seems a little odd to me, logically speaking if a WiFi hotspot detector picked up a signal from a WiFi laptop. Then it would give positive results if you have a laptop on you regardless of where you are and would be correspondingly useless to find hotspots.
Possibly it's being used to find hotspots on the theory that WiFi owners are more likely to park in areas where there's a signal, thus improving the chance of success for the thief ?

  Riverboy 14:50 29 Jul 2005

I still do not understand how the police can state so categorically that a Wi-Fi enabled laptop still emits a signal when switched off. Any ideas?

  Belatucadrus 15:01 29 Jul 2005

Perhaps they can be triggered to respond if they've got "Wake on LAN" set, but that's going to need something rather more complex than a Hotspot finder.

  anchor 15:30 29 Jul 2005

I don`t know if this is true or not. However, if anyone is really worried, just remove the battery from the laptop.

  Riverboy 16:14 29 Jul 2005


Thanks but having stated the obvious you have missed the point. What I want to know is (1)whether or not it is possible for a Wi-Fi enabled laptop to emit a signal when it is switched off, and how/why, and (2)how will a Bluetooth hotspot finder be able to measure the strenght of any signal being emitted by a laptop that is switched off? I simply do not understand it.

  anchor 16:58 29 Jul 2005

Personally I doubt it, but will leave it for the experts to give a definitive reply later.

  Fruit Bat /\0/\ 18:54 29 Jul 2005


so have spnt the last couple of hours running an RF moitor over my HP omniook wireless enabed laptop.

Can't find a signal so far!

  Arnie 19:21 29 Jul 2005

It would be feasible to use a metal detector to seek a laptop in a car. The detector would not be able to look through the metalwork of the car but possibly through glass. Even then it could be seeing a set of spanners or some other metallic material.

Personally I think the whole thing is a hoax.

click here

For the more technical.

Switch off the laptop, remove the battery and connect a digital multimeter (DMM) in series with the battery and the laptop.

Set the DMM to a fairly high current range.

Switch on the laptop and switch down the DMM to a lower mA range. If no current is being taken it is impossible for the Wi-Fi sytem or any other circuitry to be working except the bios maintained by the small battery on the motherboard.

A far more worrying scenario is this.

click here

  woodchip 19:50 29 Jul 2005

It cannot detect a Laptop that is Switched of

  Arnie 23:06 29 Jul 2005


"Switch on the laptop and switch down the DMM to a lower mA range".

Should have read:

Make sure the laptop is still switched off and switch down the DMM to a lower mA range.

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