Criminals guess card details ‘in six seconds’

Criminals can work out the card number, expiry date and security code for a Visa debit or credit card in as little as six seconds using guesswork, researchers have found.

Experts from Newcastle University said it was “frighteningly easy” to do with a laptop. Fraudsters use a so-called Distributed Guessing Attack to get around security features put in place to stop online fraud. Researchers found the system did not detect cyber criminals making multiple invalid attempts on websites in order to get payment card data.

According to a study published in the academic journal IEEE Security & Privacy, that meant fraudsters could use computers to systematically fire different variations of security data at hundreds of websites simultaneously.

Within seconds, by a process of elimination, the criminals could verify the correct card number, expiry date and the three-digit security number on the back of the card.

Mohammed Ali, a PhD student at the university’s school of computing science, said: “This sort of attack exploits two weaknesses that on their own are not too severe but when used together, present a serious risk to the whole payment system.

“Firstly, the current online payment system does not detect multiple invalid payment requests from different websites.

Secondly, different websites ask for different variations in the card data fields to validate an online purchase. This means it’s quite easy to build up the information and piece it together like a jigsaw.”

Visa said: “The research does not take into account the multiple layers of fraud prevention that exist within the payments system, each of which must be met in order to make a transaction possible in the real world.

“For consumers, the most important thing to remember is that if their card number is used fraudulently, the cardholder is protected from liability.”