The Chinese-linked Salt Typhoon cyberespionage operation targeted AT&T and Verizon's systems, but the wireless carriers' US networks are now secure as they work with law enforcement and government officials.
"We detect no activity by nation-state actors in our networks at this time. Based on our current investigation of this attack, the People's Republic of China targeted a small number of individuals of foreign intelligence interest," an AT&T spokesperson said.
While only a few cases of compromised information were identified, AT&T was monitoring and remediating its networks to protect customers' data, and continues to work with authorities to assess and mitigate the threat, the spokesperson said.
"We have not detected threat actor activity in Verizon's network for some time, and after considerable work addressing this incident, we can report that Verizon has contained the activities associated with this particular incident," Verizon's chief legal officer said in a statement.
An independent and highly respected cyber security firm has confirmed the containment, Verizon said.
On December 27, US officials added a ninth unnamed telecom company to the list of entities compromised by the Salt Typhoon hackers and said the Chinese involved gained access to networks and essentially had broad and full access, giving them the capability to "geolocate millions of individuals, to record phone calls at will."
The U.S. Department of Defense and the Federal Communications Commission did not immediately respond to Reuters' requests for comment on the company statements. China's foreign ministry could not immediately be contacted for comment.
Chinese officials have previously described the allegations as disinformation and said Beijing "firmly opposes and combats cyber attacks and cyber theft in all forms."
Officials previously alleged hackers targeted Verizon AT&T, Lumen and other telecom companies, and stole telephone audio intercepts along with a large swath of call record data.
In response to that cyberattack, the US Cybersecurity and Infrastructure Security Agency on December 18 urged senior government and political figures to move mobile communications to end-to-end encrypted apps.
Targets of Salt Typhoon reportedly included officials connected to Democrat Kamala Harris and Republican Donald Trump's presidential campaigns.
Senator Ben Ray Lujan, a Democrat from New Mexico, called Salt Typhoon the "largest telecommunications hack in our nation's history" during a December 11 hearing, while Texas Republican Senator Ted Cruz said the US "must plug any vulnerabilities in communications networks."
There is growing concern about the size and scope of the reported Chinese hacking into U.S. telecommunications networks and questions about when companies and the government will be able to assure Americans about the issue.
