AT&T has admitted that hackers have broken into one of its systems to access the personal data on thousands of its US customers.
Customers affected were those that used an AT&T online store, and the information illegally accessed includes credit card numbers.
Around 20,000 customers are said to be affected. They had used the site to buy equipment for their broadband connections.
The data breach took place last weekend and the credit card companies of customers have been notified along with the customers, via e-mail, phone and letter.
AT&T is offering free credit checking facilities to affected customers, in case they become victims of identity theft.
Earlier this month, AT&T sought to tackle another data breach problem. It filed a suit in a federal court to block two dozen data brokers from accessing customer information without authorisation from the company or the customer.
At the time, Priscilla Hill-Ardoin, chief privacy officer at AT&T, said, “We're taking this action on behalf of our customers. We intend to vigorously pursue these individuals who, through fraud, have attempted to obtain unauthorised access to customer information.”
In some cases, said the company, individuals or data brokers had used unauthorised access to telephone records, often to collect information for use in legal or domestic disputes.
Hill-Ardoin said that an AT&T internal investigation identified about 2,500 customers as “possible victims of data brokers”. The customers involved have already been notified and access to their online accounts has been frozen for their protection.
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