US senator demands AT&T and Verizon CEOs testify over Salt Typhoon telecom hack

US Senator Maria Cantwell (D-WA) is calling for AT&T and Verizon's top executives to testify on Capitol Hill, accusing the US telecoms of blocking the release of security assessments tied to the Chinese nation-state actor Salt Typhoon and questioning the current state of the telecoms' network security.

The lawmaker said both telecom giants refused to provide network security assessments conducted by cybersecurity firm Mandiant, despite repeated requests from lawmakers seeking clarity on whether the companies’ networks are now secure.

In a letter published Tuesday, addressed to Ted Cruz, Chair of the Senate Committee on Commerce, Science, and Transportation, Cantwell alleged that Mandiant, the threat intelligence arm of Alphabet's Google, declined to provide the requested assessments “apparently at the direction of AT&T and Verizon.”

Lawmakers have described the intrusions as the worst telecom breaches in US history.

“If AT&T and Verizon are not going to provide Congress key documentation voluntarily, then I believe this committee must promptly convene a hearing with their CEOs so they can explain why Americans should have confidence in the security of their networks amid mounting evidence that the Salt Typhoon hackers remain active and undeterred,” she said.

Other major US carriers, including T-Mobile and Viasat, as well as an unnamed Canadian telecom, have also reported being hacked as part of the Salt Typhoon espionage campaign.

Neither Verizon, Mandiant, nor AT&T has yet to publicly comment on the matter.

FBI warns of sweeping global impact

Cantwell pointed to public statements from the FBI warning that Salt Typhoon targeted more than 200 US organizations and 80 countries.

The senator said the campaign allowed Chinese intelligence officers to potentially surveil Americans’ private communications abroad and use cellphone geolocation data to track movements worldwide.

The Chinese government has repeatedly denied responsibility for the attacks.

In some cases, hackers were said to have intercepted dozens of conversations, including those involving prominent US politicians and government officials.

The Chinese espionage group is said to be behind a years-long espionage campaign targeting US telecoms that has led to breaches at the US Treasury, infiltrating the laptops of multiple senior banking officials, as well as the US National Guard.

Further attacks were discovered targeting the email accounts of US Congressional aides and campaign staffers during the lead-up to the 2024 US Presidential election, including former US President Joe Biden, Vice President Kamala Harris, and then-candidate US President Donald Trump and running mate JD Vance.

In December it was revealed that two suspected members of Salt Typhoon had once been students in a global training program run by Cisco.

Cantwell said the Salt Typhoon operation allowed the Chinese government to “geolocate millions of individuals” and “record phone calls at will,” adding that the incident targeted “almost every American.”

"AT&T and Verizon have 265 million customers. How many are still exposed to Salt Typhoon?"

- US Senator Maria Cantwell (D-WA)

Ongoing security concerns

In a separate statement, Cantwell said she had sought documentation from AT&T and Verizon since early last year to corroborate their claims that their networks are now secure.

“For months, I have sought specific documentation from AT&T and Verizon that would purportedly corroborate their claims that their networks are now secure from this attack,” she wrote.

“Unfortunately, both AT&T and Verizon have chosen not to cooperate, which raises serious questions about the extent to which Americans who use these networks remain exposed to unacceptable risk.”

She also cited testimony from cybersecurity experts who warned that Salt Typhoon may not have been fully removed from telecom networks.

According to Cantwell, “experts believe the Salt Typhoon attack has not been fully remediated from telecommunications networks, and there is increasing evidence that companies like AT&T and Verizon are not taking the actions necessary to protect their 265 million customers.”

Cantwell referenced testimony from a former Federal Communications Commission (FCC) official who told lawmakers in December, “I’m not convinced that providers will take sufficient and sustained actions in the wake of Volt and Salt Typhoon without a strong verification regime.”

“If the providers are not doing basic hygiene across their networks consistently, then yes, they should be held accountable,” the former FCC head added.

Pressure builds for oversight hearing

Cantwell said she also requested documents directly from Mandiant after AT&T and Verizon failed to cooperate.

However, she said both companies intervened to block the cybersecurity firm from sharing the reports.

“I believe this course of engagement raises serious questions about AT&T’s and Verizon’s current security posture, as they are either unwilling or unable to provide specific documentation that would show their networks are secure,” she wrote.

The senator is now urging the Senate Committee to convene an oversight hearing so the CEOs of both telecom giants can testify publicly.

“The American public deserves transparency and certainty that our nation’s major telecommunications networks are not currently exposed to unacceptable risks,” Cantwell wrote. “This oversight hearing would be an opportunity to provide precisely that.”

More than a dozen Chinese nationals were indicted by the US Department of Justice 2024 in connection with the telecom attacks, as well as individual and corporate sanctions imposed on the perpetrators by the Treasury’s Office of Foreign Assets Control (OFAC).

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