Theft of goods from vehicles after a victim’s car remote has been jammed has become a regular occurrence in South Africa.
Despite the security features of modern cars, criminals have discovered a simple way to get into a vehicle: prevent the owner from locking it.
While this relies on victims not noticing their car didn’t lock, car jamming is easy enough that finding the right target doesn’t cost much.
Criminals don’t need illegal instruments or technical expertise to get started – all they need is a gate or garage remote with a sufficiently-powerful transmitter.
Because most short-range remote controls, such as those used by cars and automated gates, use common frequencies to communicate, a gate remote that puts out a more powerful signal on the same frequency as the remote of your car can easily “drown out” its message.
“It’s like trying to talk to someone while another person in the room is making a lot of noise,” said SensePost security researcher Chris Le Roy.
Watch how car remote jamming works
In the video below, Le Roy demonstrates how car remotes can be jammed.
A popular frequency band used in South Africa is 433MHz, which has been reserved for unlicensed use by short-range devices such as remote controls.
Manufacturers are able to build devices that use unlicensed frequency bands without getting a spectrum licence from Icasa.
The power of the signal of such a device is restricted, which means you don’t need a strong signal to jam it.
There are also “professional-grade” jammers that operate across a number of different frequencies and at higher levels of power.
These jammers can interfere with a vehicle remote at greater distances than the 5-10 metres afforded by gate remotes.
Remote jamming detection
To see if there’s an easy way to combat remote jamming, Le Roy and another security researcher, Stuart Kennedy, built a detector that can measure when frequencies in the 433MHz band are being jammed.
He said the hardware is simple, composed of an Arduino microcontroller kit and a radio chip that can pick up 433MHz signals.
The magic of the detector happens in its software, where it establishes a baseline for the level of noise on the frequency band in the immediate vicinity, and then reacts when there is a disturbance.
Le Roy said they are looking at building a device that would alert you – by buzzing in your pocket, for example – when it detects remote signal jamming in the area.
Drivers who don’t have jamming detectors will have to take other precautions to ensure they don’t fall victim to remote jamming. Most importantly:
- Manually check that your car is locked before walking away.
- Never leave valuables in your car.