AT&T is notifying millions of customers of data breach after a third-party vendor hack

Pierluigi Paganini March 10, 2023

AT&T is warning some of its customers that some of their information was exposed after the hack of a third-party vendor’s system.

AT&T is notifying millions of customers that some of their information was exposed after a third-party vendor was hacked.

CPNI is information related to the telecommunications services purchased by the customers, including the number of lines for each account or the wireless plan to which customers are subscribed.

“We recently determined that an unauthorized person breached a vendor’s system and gained access to your “Customer Proprietary Network Information” (CPNI).” reads a data breach communication sent by the company to the impacted customers. “However, please rest assured that no sensitive personal or financial information such as Social Security number or credit card information was accessed.”​

Exposed data don’t include financial information (i.e. credit card data) or sensitive data (i.e. Social Security Number, account passwords).

The vendor was hacked in January, and AT&T told its customers that vulnerability exploited by the attackers has been already fixed. The Telco giant added that its systems were not compromised.

The company has notified federal law enforcement, but the data breach notification does not provide the number of impacted customers.

“Our report to law enforcement does not contain specific information about your account, only that the unauthorized access occurred.​” continues the notice.

BleepingComputer reported that approximately 9 million wireless accounts were impacted.

The company recommends its customers to add an “extra security” password protection to their account at no cost.

On August 2021, ShinyHunters group claimed to have obtained a database containing private information on roughly 70 million AT&T customers, but the company denied that they have been stolen from its systems.

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Pierluigi Paganini

(SecurityAffairs – hacking, AT&T)

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