Mobile phone security cards can be cloned in minutes allowing hackers to make calls charged to their victim's account, according to research from IBM.
In a paper to be presented at a major security symposium next week, Big Blue will reveal that hackers can discover the security number of a GSM phone in minutes.
The process, known as a 'partitioning attack', involves the analysis of power flows in the phone's SIM card, which can determine the codes inside.
But the process requires the hacker to be alone with the phone for a minute or two using IBM's 'seven questions' routine for deciphering the PIN code, and only affects so-called 'first-generation' phones.
IBM stressed that it was not a "sky is falling" announcement, but more a proof of concept to show that the technology could be developed into a potential threat.
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago