T-Mobile hacked? T -Mobile is investigating a data breachafter a hacker claims to have breached the company's servers and stolen databases containing personal data of about 100 million customers.

T-Mobile hacked: Data on hacking forum
The hacker announced the data breach on a hacking forum, after saying he was selling a database for six bitcoins (~$280K). According to him, the database contained birth dates, driver's license numbers, and social security numbers for 30 million people.
See also: Hackers use PrintNightmare to hack Windows servers
The forum post did not mention the origin of the data, but the hacker told BleepingComputer that the stolen data belonged to T-Mobile customers, which was obtained through a massive breach of the company's servers.
The hacker claims to have broken into production, staging and development servers about two weeks ago, while also breaching an Oracle database server containing customer data.

This stolen data is said to contain data for approximately 100 million T-Mobile customers and may include IMSI, IMEI, phone numbers, customer names, PIN codes, social security numbers, driver's license numbers, and dates of birth of customers.
See also: T-Mobile, AT&T, Verizon: What measures are they taking to reduce robocalls?
IMEI (International Mobile Equipment Identity) is a unique number used to identify mobile phones, while IMSI (International mobile subscriber Identity) is a unique number associated with a user on a mobile network.
As evidence of the breach of T-Mobile's servers, the attacker(s) shared a screenshot of an SSH connection to a production server.
Cybersecurity firm Cyble told BleepingComputer that the hacker claims to have stolen multiple databases (106 GB of data), including T-Mobile's CRM (customer relationship management) database.

The attacker(s) never contacted the company to demand a ransom and decided to sell the stolen data on a hacking forum.
See also: #KartaGate: The Commissioner for Personal Data Protection confirms the breach
T-Mobile is investigating the incident: “We have learned of the claims made by a hacker on an underground forum and are investigating their validity. We have no additional information to share at this time,” T-Mobile told BleepingComputer.
T-Mobile: Vengeful motives for hack
The hackers said the breach was vindictive and was done to damage US infrastructure.
Source: Bleeping Computer
