When the Navy Criminal Investigative Service started looking into a breach of one of their low-security networks, the team got an unpleasant surprise: at least one of the culprits was a Navy sailor, performing the attacks from an aircraft carrier at sea.

The hacking group called Team Digi7al breached at least 24 websites in 2012, including the Navy's own SmartMove system, used to help sailors coordinate changes of address. The team was looking for social security numbers and other personal data, the raw material for identity theft, targeting sites like the Toronto Police Service and Stanford University. For the most part, the attacks were small enough to stay under the radar — but when a tweet posted to Team Digi7al's Twitter account from an internal Navy network, NCIS realized the SmartMove attack had been an inside job, and sprang into action.

It took an elaborate sting operation to find Digi7al's inside, including a fake database designed as an attractive target, but finally NCIS traced the breach back to Nicholas Paul Knight, the systems administrator for the nuclear reactor onboard the USS Harry Truman aircraft carrier. On Tuesday, Knight plead guilty to charges of identity theft and obstruction of justice in federal court. He faces five years in prison and a $250,000 fine.