Although the stolen data did not include the names associated with the phone numbers, that information would probably be easy to reverse-engineer using online data brokers and public records. The hack also affected non-AT&T customers of mobile virtual network operators who were using the company’s wireless network.
The company learned about the hack on 19 April, according to the filing, and is working with law enforcement efforts to find the perpetrators. It follows another hack of AT&T’s data that it
disclosed in March, which did contain the personal information, including social security numbers, of millions of users.