One upon a time electronic tracking person [target] was expensive, and difficult to achieve, but with the advancement of technology, it is now just a matter of a few pounds, and the leverage of available technology.
After setting up a compromised Cell Phone, with an invisible backdoor application to track, duplicate and send SMS etc. and to follow the owner/target, I ran an experiment, and with the ‘permission’ of a subject individual, and had them carry the device for a few days.
The results are remarkable when you consider the low cost of such a tool – I have been able to map their movements, link them to locations by time, and cross relate to simple technologies such as Google Maps, and Street View. With a little more configuration, I have also been able to track every web site they visited, and received every SMS etc. sent, and received, and have had a duplicated copy of every image communication, and all unbeknown to the target.
Of course it is all very well recoding such sessions, but the determined attack/watcher also wants to receive regular reports – simple, this is either done via sending messages direct to a subscribed mobile, or to the associated web interface. And of course if you [the attacker] wish to remove, or update the application on the target Cell Phone, this may all be done remotely, and without any need of physical access.
Simple technology, and one good reason why you should never let your cell phone out of your view – the question is, when it comes back, it is clean?