Security researchers have revealed a $1400 technology which can be used to exploit the security flaw in 4G enabled smart phones to locate precise location of the apps users by simply messaging them.

According to researchers from Aalto University, the University of Helsinki, Technische Universitat Berlin and Telekom Innovation Laboratories, a hacker can use the apps to discover the supposedly anonymised identifiers that are assigned to devices when they connect to a network, and use them to locate their owners.

It was discovered that when a smartphone connects to a mobile network, it is assigned a temporary number called a TMSI (Temporary Mobile Subscriber Identity). The network then uses this eight-digit number to identify a device, rather than a phone number, to make communication more private.

It is this very loophole in technology that a hacker monitoring radio communications can exploit by tying this TMSI to an individual by sending them a Facebook message or WhatsApp chat, both of which trigger a special "paging request" from a network that contains specific location information about a particular TMSI number.

In the research, it was confirmed that all Facebook users are able to send messages whether friends to one another or not. In case they are not friends, the message may end up in Facebook's "other" folder, a feature unknown to many and only accessible on the social network's desktop version, but all in all messaging causes "Paging request".

In a similar way, WhatsApp's "typing notification", a feature that the chat app displays when a contact is composing a message, also triggers the paging request. If a hacker has a victim's phone number, they could send them a message on WhatsApp, and if the victim begins to type a response, the network issues a paging request.

Within these paging requests are locations data, those 4G networks can be used to track and easily pinpoint the accurate locations of all smartphone users. Older 2G and 3G networks would place a particular smartphone within a given "tracking area" of around 100km 2, representing less of a security issue, but modern 4G networks place them in smaller "cells" of around 2km, making it much easier to pinpoint a smartphone.

More aggressive attackers can set up a fake network base station to accurately triangulate users. These stations can request reports from TMSI numbers, typically used in cases of network failure, which can accurately reveal a smartphone's location. At least one device gave away its GPS co-ordinates after a failure request, the researchers said. There are now close to half a billion 4G subscriptions around the world as the number of connections grew by 140 percent during 2014, according to the Global Mobile Suppliers Association (GSA).