How cyber criminals make LIMITLESS purchases from your card by cracking the £30 contactless limit

Visa may be putting countless customers at risk of online fraud.

That’s according to cyber security experts, who say they’ve discovered flaws which allow hackers to bypass the verification limits on the company’s contactless cards.

British company Positive Technologies tested the tactic with five major UK banks, successfully bypassing the £30 maximum spend on all cards, irrespective of the terminal.  

They also found that this attack is possible outside of the UK. 

Be careful: The attack works by manipulating two data fields that are exchanged between the card and the terminal during a contactless payment

Researchers Leigh-Anne Galloway and Tim Yunusov say the attack works by manipulating two data fields that are exchanged between the card and the terminal during a contactless payment. 

Currently, if payment needs an additional cardholder verification, cards will respond by saying ‘I can’t do that’, which blocks payments over this limit. 

Secondly, the terminal uses country specific settings, which demand that the card or mobile wallet provide additional verification of the cardholder, such as through the entry of the card PIN or fingerprint authentication on the phone.

Positive Technologies found that both of these checks can be bypassed using a device which intercepts communication between the card and the payment terminal. This device acts as a proxy and is known to conduct man in the middle (MITM) attacks. 

First, the device tells the card that verification is not necessary, even though the amount is greater than £30. The device then tells the terminal that verification has already been made by another means. This attack is possible because Visa does not require issuers and acquirers to have checks in place that block payments without presenting the minimum verification.

The attack can also be done using mobile wallets such as GPay, where a Visa card has been added to the wallet. Here, it is even possible to fraudulently charge up to £30 without unlocking the phone. 

‘The payment industry believes that contactless payments are protected by the safeguards they have put in place, but the fact is that contactless fraud is increasing,’ said Tim Yunusov, Head of Banking Security for Positive Technologies. 

At risk? British company Positive Technologies tested the tactic with five major UK banks, successfully bypassing the £30 maximum spend on all cards, irrespective of the terminal

‘While it’s a relatively new type of fraud and might not be the number one priority for banks at the moment, if contactless verification limits can be easily bypassed, it means that we could see more damaging losses for banks and their customers.’

The researchers advise that contactless card users need to be vigilant in monitoring their bank account statements to catch fraud early and, if available with their bank, implement additional security measures such as payment verification limits and SMS notifications.

‘It falls to the customer and the bank to protect themselves,’ said Leigh-Anne Galloway, Head of Cyber Security Resilience at Positive Technologies. 

‘While some terminals have random checks, these have to be programmed by the merchant, so it is entirely down to their discretion. Because of this, we can expect to see contactless fraud continue to rise. Issuers need to be better at enforcing their own rules on contactless and increasing the industry standard. 

‘Criminals will always gravitate to the more convenient way to get money quickly, so we need to make it as difficult as possible to crack contactless.’

According to UK Finance, fraud on contactless cards and devices increased from £6.7 million in 2016 to £14 million in 2017. £8.4 million was lost to contactless fraud in the first half of 2018.