New research into the security of Visa credit and debit cards has described the ability to bypass online payment security methods in just six seconds as “frighteningly easy”.


According to new research conducted by Newcastle University in the UK, details of a person’s Visa credit or debit card can be obtained in as little as six seconds, using a technique known as a distributed guessing attack.


The researchers found that by automatically and systematically generating different variations of the cards security data and firing it at multiple websites, within seconds they were able to identify a ‘hit’ and verify all the necessary security data.


When a person makes a purchase online using a card, they are typically asked to provide the card number, expiry date, CVV security code at the back of the card and sometimes their address.



This attack, lead researcher Mohammad Ali said, exposes two huge weaknesses in the verification system.


‘Frighteningly easy for attackers’


This allows unlimited guesses on each card data field, using up to the allowed number of attempts – typically 10 or 20 guesses – on each website.


The first weakness indicates the lack of communication between various platforms, as current online payment systems do not detect multiple invalid payment requests from different websites.


The second weakness, the team identified, is that different websites tend to ask for different variations of details in a bid to ensure greater security, yet all it does is help a hacker to build up information on a potential large.


MasterCard unaffected

This means that if a hacker has only the first six digits of the card, they will be able to obtain the three essential pieces of information to make an online purchase within as little as six seconds.


Even the CVV number, that only the holder of the card should be able to see, can be cracked in fewer than 1,000 attempts, thanks to the fact that it is so short in length.


“Spread this out over 1,000 websites and one will come back verified within a couple of seconds. And there you have it – all the data you need to hack the account.”


Worryingly for Visa card owners, Ali and his team determined that it is only applicable to these cards, as MasterCard’s centralised network detects multiple incorrect guesses after 10 attempts.


This distributed guessing attack method, the team believes, likely played a part in the recent cyberattack against the British shopping giant, Tesco.


“The Cyberteam from the Newcastle University believes that the technique, known as a Distributed Guessing Attack, was used in the recent £2.5million hack on the 20,000 customers of Tesco bank”


Ultimately, the only way to secure payment systems against distributed guessing attacks are to centralize as Mastercard has done or standardize, with all sites requiring the same information to validate card numbers. In this way, the attack cannot be scaled, the researchers wrote.

Leave a Reply