It starts with a little 'social engineering'.

By hacking the phone of someone the victim might trust, and learning something about them from reading their Tweets and Facebook page, the attacker will send a personalised email from a known account.

The user opens an email and a document, a picture, letter or pdf file.

A programme can be embedded in the attached document which takes the hacked user's phone off to a secret website site which covertly downloads spying software onto the smartphone. "Shortened weblinks are also a risk," Mr. Hart added.

 According to Mr. Hart "Using Facebook and Twitter, and getting an individual to click on a shortened link would actually take them to a website and automatically install malware."

And the worth part of it that you never know that your phone had been hacked. 

I was shocked when I have read this article. So it basicly says that how it is easy to be a victim of a spysoftware. Spies can easily listen to my phonecalls, read my messages, know whom I talk to the most, which webpages I am entering. And after it they can use this information against me, for example. It is horrible.

So, my advice for you is not to buy expensive smartphones if you do not want to be a victim of this.