While cyber criminals continue to devise ever more creative ways to get into systems, the outcomes of repeat like a broken record: stolen data and lost money. It happened in again and again this year, but our pick proves the stakes are only getting higher with time. We'll explain the logic behind the list, impacts felt, and key takeaways.

An insider is any person with authorized access to systems or data that gives them the ability to take potentially harmful actions. Insiders range from business partners or third party contractors to full- and part-time employees–essentially all valid users with access to resources that you'd rather keep out of the wrong hands. People are just people, but when they mishandle data, they fall into the category of being an insider threat–intentional or not.