According to a report by Bloomberg on Thursday, January 16th, the leadership of the Federal Bureau of Investigation (FBI) in the United States warned that Chinese hackers who infiltrated AT&T last year may have stolen several months’ worth of call and text message records of agents. This forced the bureau to take emergency measures to protect the identities of confidential informants.
The security breach, as revealed in a document reviewed by Bloomberg News and interviews with current and former law enforcement officials, could potentially affect all FBI devices using AT&T’s public safety services, exposing agents’ phone numbers along with the corresponding numbers for their calls and texts.
Although the hackers did not manage to obtain the specific content of the calls and texts, the contact numbers acquired from the call and text records could potentially allow for the deduction of which individuals FBI agents were in contact with, thereby risking the exposure of confidential intelligence sources such as informant identities.
Last July, AT&T announced it had detected a large-scale hacker attack as early as April, resulting in the illegal download of data, including call and text records, of approximately 109 million mobile users.
At the end of last month, two major U.S. telecom companies, AT&T and Verizon, acknowledged for the first time that their systems had been targeted in attacks by a Chinese hacker group known as “Salt Typhoon.”
These companies stated that they are cooperating with U.S. law enforcement agencies and government officials, and currently, wireless communication networks in the United States are secure.
Both AT&T and the FBI did not immediately respond to Reuters’ request for comment.
According to reports, the hackers illegally obtained phone numbers of “almost all” mobile users of the company network between May 1, 2022, and October 31, 2022, as well as every number called or texted by these users during that period, including the frequency of interaction and call durations between these numbers.
This incident has raised widespread concerns about Chinese hackers targeting U.S. telecommunications networks for espionage activities.
The Cybersecurity and Infrastructure Security Agency (CISA) in the United States urged senior government and political figures on December 18 to transition mobile communications to end-to-end encrypted applications.
On January 10, White House National Security Advisor Jake Sullivan responded by stating that the United States has taken measures to address network espionage activities by China targeting U.S. telecommunications companies.