T-Mobile says telco hackers had ‘no access’ to customer call and text message logs

U.S. phone giant T-Mobile said Wednesday that hackers had “no access” to its customers’ calls, text messages, and voicemails during an ongoing industry-wide cyberattack targeting internet and phone companies.

T-Mobile’s chief security officer, Jeff Simon, said in a statement that the company detected in recent weeks “attempts to infiltrate our systems,” which Simon said originated from another telecoms company connected to T-Mobile’s network. That company wasn’t named. 

“We quickly severed connectivity to the provider’s network as we believe it was — and may still be — compromised,” Simon said. 

The Wall Street Journal reported last week that the China-backed hacking group known as Salt Typhoon had compromised T-Mobile, along with several other telecom giants, including AT&T, Verizon, and Lumen, as part of a broad espionage operation targeting the communications of U.S. officials and senior Americans, including presidential candidates.

T-Mobile said Wednesday that it could not definitively identify the identity of the hackers, but added: “We do not see these or other attackers in our systems at this time.” The company did not explicitly rule out a previous intrusion of its systems, saying that its cybersecurity defenses stopped the attackers “from accessing sensitive customer information.”

When asked by TechCrunch, a T-Mobile spokesperson said metadata about customer phone calls and text messages, such as information about the caller, sender and recipient, and the dates and times of communications, are considered “sensitive” customer records and were not accessed.

“We have robust technical means, including logs, to be able to identify threats and activity on our systems. It was this type of telemetry that enabled us to quickly identify suspicious activity and take action to protect our systems and customers,” said T-Mobile spokesperson Michelle Jacob.

T-Mobile said it invested in cybersecurity hardening over previous years, in large part because of numerous data breaches that compromised millions of T-Mobile customers’ personal information. 

U.S. cybersecurity agency CISA and the FBI said in a public alert last week that China-backed hackers were targeting telcos as part of a “broad and significant cyber espionage campaign” targeting wiretap systems, which U.S. phone and internet companies are required by law to install. 

Senior U.S. officials have linked the Salt Typhoon campaign against telcos as part of a broader effort by China to lay the groundwork for disruptive cyberattacks in the event of a future conflict with the United States, such as an anticipated Chinese invasion of Taiwan.

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