this blog is an interesting tips and tricks site: http://tipstrickshack.blogspot.com/ (also explains hackers terminology a bit)
The author describes several hacks on vulnerabilities within wordpress 3.51 (today latest is 3.8).
So if you never upgrade your software (wordpress) then it will get hacked
that is how it is, one always needs to be aware of their software updates, where if a vulnerable software will get hacked if not updated.