Researchers reveal vulnerability that can bypass payment limits in contactless Visa card

A few days ago, researchers from Positive technologies discovered flaws in Visa contactless cards, which allow hackers to bypass the payment limits. This research was conducted by two of Positive technologies’ researchers: Leigh-Anne Galloway, Cyber Security Resilience Lead and Tim Yunusov, Head of banking security.

The attack was tested with “five major UK banks where it successfully bypassed the UK contactless verification limit of £30 on all tested Visa cards, irrespective of the card terminal”, the researchers mentioned. They added that the contactless Visa card vulnerability is possible on cards outside the UK as well.

How to exploit this contactless Visa card vulnerability?

The attack manipulates two data fields that are exchanged between the card and the terminal during a contactless payment. “Predominantly in the UK, if a payment needs an additional cardholder verification (which is required for payments over 30 pounds in the UK), cards will answer "I can’t do that," which prevents against making payments over this limit,” the researchers said. Next, 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.

The attack could bypass both these checks using a device that intercepts communication between the card and the payment terminal. This device acts as a proxy thereby conducting a man in the middle (MITM) attack. “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 researchers say.

“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,” Positive Technologies mention in their post.

One of the researchers, Yunusov said, "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. 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."

A hacker can easily conduct a cardless attack

Forbes explains, criminals, for instance, could take a payment from a card when the user wasn’t looking with their own mobile payments machine (though a malicious merchant would eventually be caught by banks’ fraud systems if they used the same terminal). They could even take a payment reading from a credit card using their mobile phones and send the data to another phone and make a payment on that second device going beyond the limit, the researchers claimed.

“For the hack to work, all the fraudsters need is to be close to their victim,” Forbes mentions.

“So that means if you found someone’s card or if someone stole your card, they wouldn’t have to know your PIN, they wouldn’t have to impersonate your signature, and they could make a payment for a much higher value,” Galloway said.

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.

Researchers suggest that additional security should be provided by the bank issuing cards and shouldn’t rely on Visa to provide a secure protocol for payments. “Instead, issuers should have their own measures in place to detect and block this attack vector and other payment attacks,” the researchers say.

Galloway says, “It falls to the customer and the bank to protect themselves. 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,” she further adds.

In the U.S., contactless card transactions are relatively rare, with only about 3 percent of cards falling into this category, CNBC reports.

Researchers say the limits attackers can withdraw will differ in different countries. In the UK, they were able to make payments of £100 without any detection. Galloway says, for instance, in the U.S., it’s considerably higher at $100.

What measures is Visa taking to prevent this kind of contactless fraud?

Surprisingly, the company was not alarmed by this situation. In fact, Forbes reports that Visa wasn’t planning on updating their systems anytime soon.

“One key limitation of this type of attack is that it requires a physically stolen card that has not yet been reported to the card issuer. Likewise, the transaction must pass issuer validations and detection protocols. It is not a scalable fraud approach that we typically see criminals employ in the real world,” a Visa spokesperson told Forbes. The company also said it was continually working on improving its fraud detection tech.

https://twitter.com/a66ot/status/1155793829443842049

To know more about this news in detail, head over to Positive technologies’ official post.

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