Hackers in foreign countries generate a lot of news headlines, as evidenced by last week's news that a Russian crime ring may have stolen stolen more than a billion usernames and passwords. But individuals much closer to your business--like former employees--could represent your company's greatest cybersecurity threat.

Roughly 90 percent of respondents to a recent survey reported that they retained a working login and password to at least one application from their former employer, according to cloud IT services company Intermedia.

The infographic below demonstrates some of the ways you can prevent rogue employees from harming your business.