US officials have warned people to not send text messages amid a massive and ongoing cyber attack against telecom companies.
Smartphone users are instead urged to use encrypted messaging apps like Signal or WhatsApp in order to communicate safely between Android and iPhone devices.
The cyber campaign, referred to as Salt Typhoon, stems from Chinese hackers, according to the FBI and the US cyber defence agency CISA.
“Threat actors affiliated with the People’s Republic of China (PRC) are targeting commercial telecommunications providers to compromise sensitive data and engage in cyber espionage,” said Bryan Vorndran, assistant director of the FBI’s Cyber Division.
“Together with our interagency partners, the FBI issued guidance to enhance the visibility of network defenders and to harden devices against People’s Republic of China-affiliated exploitation.”
The Salt Typhoon cyber campaign was described by one senator as the “worst telecom hack in our nation’s history”.
Senator Mark Warner, who is chairman of the Senate Intelligence Committee, told the Washington Post last month that the cyber attack was unprecedented in scale.
“This is an ongoing effort by China to infiltrate telecom systems around the world, to exfiltrate huge amounts of data,” he said.
FBI Director Chris Wray has previously described strong encryption as “an urgent public safety issue”, with the latest report from the agency suggesting that hackers are still within the networks of major telecom companies like T-Mobile.
“Our suggestion, what we have told folks internally, is not new here: Encryption is your friend, whether it’s on text messaging or if you have the capacity to use encrypted voice communication,” Jeff Greene, executive assistant director for cyber security at CISA, told reporters on Tuesday.
“Even if the adversary is able to intercept the data, if it is encrypted, it will make it impossible.”
The hackers have already stolen large tranches of data and phone intercepts, according to US officials, with Mr Greene saying it would be “impossible to predict” when the hackers might be evicted from the phone networks.
