A rogue employee is a worker who undermines the organization that employs him by failing to comply with its business rules and policies. The rogue worker might openly flout company rules, which may mean he won’t remain in the position for a long time. On the other hand, a rogue employee might covertly subvert the company while attempting to escape detection by appearing compliant -- in which case he might remain on the job for an extended period of time.
A rogue employee’s actions might be relatively innocuous or serious enough to pose a risk to business continuity. In the worst-case scenario, a rogue employee is an insider threat, actively working to undermine the organization, possibly engaging in industrial espionage and sharing sensitive corporate data with a competitor.
Even if the employee's actions aren’t intended to cause harm, however, situations involving any significant number of employees can have a serious impact. The current trends of IT consumerization and bring your own everything (BYOX), for example, mean that consumer devices and applications have invaded the business environment, complicating and problematizing both administration and security.
The word rogue probably originates from the Old Middle English slang roger, for “a begging vagabond pretending to be a poor scholar from Oxford or Cambridge.” The first citations of the phrase “to go rogue” come from the 1920s, in reference to lone elephants that broke away from the herd and began to behave destructively.