Bob Felts is 100% correct.
Also if your using a Apple or Android device, there are a ton of exploits which can cause this, and it is increased greatly if you log onto public or hotel networks. Sadly Apples time of it was not a major player so no one wasted there time is long gone and Apple has been slow to admit there behind the times in security software.
In the U.S. the NSA, in Russia the banking system, and China's trade system have all shown, you can pay millions and people still get exploits in.