BELLEVUE (dpa-AFX) - Hackers have gained access to data on around 37 million customers of Telekom subsidiary T-Mobile US. The company announced this on Thursday after the U.S. stock exchange closed. The cyber attack was detected on January 5, according to the statement. With the help of external experts, the source of the attack was found and it was stopped within a day of becoming known. Investigations are still underway, but there are currently no indications that it was possible to penetrate the system or network.

Nevertheless, the U.S. wireless carrier, which is part of the Bonn-based Deutsche Telekom Group, did not rule out the possibility that the incident, which began on or around Nov. 25, could result in high costs. T-Mobile shares initially fell a good two percent in after-hours U.S. trading. However, according to the company, the incident does not involve highly sensitive customer data. According to preliminary findings, telephone numbers, birth data and billing addresses may have been captured, but not passwords, credit card or social security numbers.

Based on the investigation so far, customer accounts and financial data were not directly at risk, T-Mobile said. However, the investigation was ongoing. The company has repeatedly been targeted by cyber criminals in recent years. In 2021, T-Mobile was the victim of an attack in which data on more than 40 million former customers and prospective buyers fell into the hands of hackers, according to the company at the time. In 2015, sensitive data on more than 15 million T-Mobile customers was accessed in an attack on a service provider's servers./hbr/mis/DP/stk