The worst hacks of all time

In late 2013, Target revealed that 110 million customer accounts were hacked.

Target got hit with the attack at the worst possible time: peak holiday shopping season. Hackers managed to break into Target's payment system by stealing computer logins from a company that, at the time, did heating and air-conditioning services for Target.

The hackers stole 40 million credit card numbers and personal informaton from 70 million online accounts.