With respect to the balance of the data set, which includes personal information such as social security numbers, the source of the data is still being assessed.
AT&T has launched a robust investigation supported by internal and external cybersecurity experts. Based on our preliminary analysis, the data set appears to be from 2019 or earlier, impacting approximately 7.6 million current AT&T account holders and approximately 65.4 million former account holders. ... .We help more than 100 million U.S. families, friends and neighbors, plus nearly 2.5 million businesses, connect to greater possibility.