One of my roles is managing our Internet Abuse Team. Waves of issues seem to change by area and come and go like the tide.
Although not really OS or application dependent, currently, the biggest issue we are tracking on our networks is phishing emails originating from a couple of countries in South America.
They start by sending out emails that look like they came from your Internet provider with some excuse as to why you should send them your user name and password. If you are silly enough to do so, they take over your mailbox and use it to send further phishing messages pretending to be financial institutions.
It's not a new thing at all, just happens to be the current hot problem of the day for the last month or so.
