Getting text messages from friends or loved ones is always welcome. Spam messages from companies can be a nuisance. Having someone unlock and start your car with a text message is much more concerning.

Unfortunately, it's not impossible, and researchers from San Francisco security consulting firm iSec Partners will be proving it at the Black Hat Security Conference in Las Vegas, starting on July 30th.

It turns out that text messaging can be quite powerful. iSec claims that they can theoretically be used to take over a power plant or water-treatment facility, and particularly easy to steal a car with the right knowledge. It's known as "war texting", which involves hacking into a cellular-network-connected device via tex message.

So many new vehicles are connected to cellular networks, often as part of their security features. General Motors' OnStar is one such system, connected to call centers and GPS satellites. Operators at these call centers can, if necessary, unlock, track and start cars remotely. BMW uses a similar system, as do many other manufacturers.

The researchers, Don Bailey and Matthew Solnik, haven't revealed which system they were able to hack into.

They claim it wouldn't take much for a hacker with similarly advanced knowledge to send a text message that allows them to break into this same system, allowing them access to all the remote services. iSec will be demonstrating how easy it is at the Black Hat conference.

So what can you do to prevent your car being stolen?

It's good news for anyone whose car doesn't use the very latest technology of course, as any car not connected to the outside world cannot be hacked into and your only worry then is theft by more "traditional" means.

For anyone with cars equipped with the latest high-tech infotainment and connected systems, you still shouldn't worry too much just yet. You still have a car with the latest security, and in the unlikely event that your car is stolen by these means, security companies should still be aware of any theft, directing the authorities to the car and safely shutting it down.

As ever though, vigilance is the best prevention.