Wireless carrier T-Mobile on Thursday fessed up to another massive data breach affecting  approximately 37 million current postpaid and prepaid customer accounts.

In a filing with the Security and Exchange Commission (SEC), T-Mobile said that an unidentified malicious actor abused an API without authorization to access customer account data, including name, billing address, email, phone number, date of birth, T-Mobile account number and information such as the number of lines on the account and plan features. 

The telco provider said the data stolen did not include payment information, passwords or other sensitive data. 

T-Mobile said the data breach was detected on January 5 this year and was contained “within a day of learning of the malicious activity.”

“Our investigation is still ongoing, but the malicious activity appears to be fully contained at this time, and there is currently no evidence that the bad actor was able to breach or compromise our systems or our network,” T-Mobile said.

The company said its systems and policies prevented the most sensitive types of customer information from being accessed, and as a result, based on our investigation to date, customer accounts and finances were not put at risk directly by this event. 

From the 8-K filing:

This isn’t the first time T-Mobile has scrambled to contain a major data breach.

Last year, the notorious Lapsus$ cybercrime gang compromised T-Mobile systems in a hacking carnage that led to source code access and access to an internal customer account management tool, which could be used to conduct SIM swapping.

T-Mobile has also disclosed data breaches affecting customer data in 2019 and 2020, and an incident that impacted more than 54 million customers in 2021. Last November, authorities in 40 U.S. states reached a settlement totaling more than $16 million with Experian and T-Mobile over data breaches suffered by the companies in 2012 and 2015.

According to the results of a survey released this week of more than 400 US-based professionals (more than 90% of whom were developers or security people), 53% claimed to have suffered an API breach, while 77% claimed their company was very or extremely effective in managing their tokens.

By Ryan Naraine on Fri, 20 Jan 2023 01:01:01 +0000
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