Hackers stole the data of 37 million customers of the US phone company T-Mobile, the company said Thursday in a filing filed with the US Securities and Exchange Commission.
The hackers, who have not been identified, broke into the company's network in November and obtained the
names, dates of birth, phone numbers and addresses
of millions of customers.
The company learned of the cyberattack on January 5 with the help of experts, who helped stop the leak shortly after the discovery.
"We understand that an incident like this has an impact on our customers and we are sorry that this has occurred," T-Mobile said in a statement.
"Our investigation is still ongoing, but it appears the malicious activity is fully contained at this time."
The company had already been the victim of a data theft in 2021.Getty Images
The company added that those who "maliciously" hacked into its system did not have access to more sensitive data such as passwords, bank account or credit card information, Social Security numbers or other government identification.
However, the information the criminals obtained could be used to get hold of some of that more sensitive data.
T-Mobile said it is in contact with federal authorities and has begun notifying customers whose information has been compromised.
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It is not the first time that T-Mobile has faced a large breach.
In 2021, 77 million company customer accounts were affected by a similar cyberattack.
On that occasion, the criminals did obtain Social Security numbers and driver's license data.
Other leaks occurred in 2019 and 2018.
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The company ended up paying $350 million to resolve customer complaints and committed to spending $150 million to repair and harden its computer systems.
T-Mobile says the company has made "substantial progress" in terms of security, but acknowledged that it requires "significant spending" to protect against such attacks in the future.
Bellevue, Washington-based T-Mobile became one of the largest cell phone carriers in the United States in 2020 after buying competitor Sprint.