According to The New York Times, hackers have been calling up Verson, T-Mobile US, Sprint and AT&T, asking them to transfer the control of a phone number, in a bid to reset the devices passwords, using the phone number as a security backup.

The Federal Trade Commission data showed the amount of hijackings rising in the United States, with 1,038 incidents reported by January 2013, which grew to 2,658 by 2016.

Chris Burniske, a virtual currency investor who lost control of his phone number late last year, said to The New York Times: “My iPad restarted, my phone restarted and my computer restarted, and that’s when I got the cold sweat and realised this was serious.”

Attackers appear to be focusing on anyone who has spoken on social media about owning virtual currencies, or who has invested in virtual currency companies.

A Bitcoin entrepreneur, Joby Weeks, revealed to The New York Times: “Everybody I know in the cryptocurrency space has had their phone numbers stolen.”

Weeks lost a million dollars through his phone number worth of virtual currency late last year, despite asking his mobile phone provider for extra security after his family lost their numbers, according to the American news source.

“It’s really highlighting the insecurity of using any kind of telephone-based security,” said Michael Perklin, the chief information security officer at the virtual currency exchange ShapeShift.

Mobile phone carriers have said they are trying to prevent attacks by adding more complex personal identification numbers.

Written by Leah Alger