According to the UK Government’s 2014 cybersecurity survey, 81% of large businesses have suffered malicious data breaches. That suggests almost one in five didn’t. But how can those companies be sure?Working out whether you’ve been hacked by cybercriminals is like leaving your diary in your bag while you visit the bathroom. When you get back, everything might still be in your bag, but you can’t be certain that no one sneaked a peek.
http://www.theguardian.com/technology/2015/mar/23/how-to-tell-if-youve-been-hacked