Consumers love the convenience of paying for goods and services in store by using their NFC enabled smartphones and stored credit cards. This is demonstrated by the fact that you can download retailer specific apps for your smartphone to pay for everything from coffee, to movie tickets, to poutine using a retailer specific mobile app.
As more and more retailers embrace this technology and release their own mobile apps with in-store payment options, the threat of fraudsters looking to benefit from flaws in the implementation, or by exploiting the human component must be carefully considered. The following are a few example Card Not Present (CNP) fraud schemes that retailers who offer in-store purchasing using a store branded mobile app should be aware of.
In these scenarios, we will use the imaginary retailer Smoothie Shop. Smoothie Shop has a mobile app that allows customers to save their credit card in the app in order to facilitate easy in-store purchases. Consumers log into their Smoothie Shop account using an email address and password. Smoothie Shop has recently seen an increase in CNP fraud and chargebacks, but is unable to pinpoint the root cause.
(Smoothie Shop mobile app login)
CNP Fraud Scheme #1 – Fraudster takes over a Smoothie Shop account that has a Credit Card saved in the app
In this scenario, the fraudster has to take over an existing Smoothie Shop account. This is known in the industry as Account Takeover (ATO) which is explained here.
In this scenario the fraudster has lucked out! Since the account that was taken over by the fraudster already has a credit card saved in the app, the fraudster can simply walk over to a Smoothie Shop, present the mobile app with the saved credit card information and enjoy a refreshing smoothie that was paid for via some other Smoothie Shop customer’s stored credit card.
CNP Fraud Scheme #2 – Fraudster takes over a Smoothie Shop account that does not have a Credit Card saved in the app
Again this scenario requires the Frauster to take over an existing Smoothie Shop account, however this scenario requires a little bit more legwork, and is less profitable as Fraud Scheme #1 above. Since the Smoothie Shop account that was taken over does not have a credit card saved in the app, the fraudster will instead need to buy a stolen credit card off the Dark Web or some other electronic market*, and then add the freshly purchased credit card to the Smoothie Shop account and app. Once this is done, the fraudster proceeds in-store to obtain smoothies using the stolen credit card.
Why would the fraudster go through the trouble of taking over an existing Smoothie Shop account you ask? Good question! Fraudsters are aware that aged accounts (e.g. accounts more than 3-6 months old) with a good transaction history are usually given more leeway and transactions from these accounts are less closely scrutinized when compared to a brand new account with no transaction history.
*Stolen credit cards can be acquired for as little as $3 or as much as several hundred dollars depending on the credit limit, zip/postal code, issuing bank, etc.
(screenshot from Dark Web Credit Card market)
CNP Fraud Scheme #3 – Fraudster creates a brand new Smoothie Shop account
This scheme doesn’t require taking over an existing account, but instead requires the fraudster to use a bot tool or a human clickfarm to create hundreds of “fake” Smoothie Shop accounts. Once the fraudster has access to multiple Smoothie Shop fake accounts, he can then add in as many stolen credit cards as he pleases in order to make in-store purchases at Smoothie Shop, each one being a unique incident of CNP fraud.
(In-store payment via Smoothie Shop mobile app and stored credit card)
What can Retailers and Consumers do to protect themselves?
Prevention Methods for Retailers
1) Prevent Account Takeover. This is easier said than done. There are many ways to prevent or at least significantly reduce the amount of ATO, such as by eliminating Credential Stuffing. The goal of the organization should be to eliminate the economic advantage that fraudsters obtain from taking over an account. If the cost/effort of taking over an account outweighs the value of said account, there will be no incentive for the fraudster and he/she will likely go elsewhere to commit fraud.
2) Maintain control of Account Creation process. Creation of accounts by bots and scripts can be limited by using a CAPTCHA, however captchas can be bypassed by mid-level sophistication fraudsters, and consumers generally dislike captchas. Preventing bulk creation of accounts requires collecting device level information in order to restrict the number of new accounts that can be created by a single device. There are device farms available for rent, but forcing the fraudster to leverage a device farm could make their rate of return less desirable and push the fraudster elsewhere.
3) Ensure your customers are not logging into your site/mobile app with credentials that have been compromised in 3rd party data breaches. This is a NIST recommendation that makes a lot of sense in today’s world of daily breaches. The customers that are logging in to your website or mobile app with compromised credentials are most likely the accounts that will be taken over and defrauded first.
4) Build controls around misuse of credit cards in the mobile app. Legitimate customers will likely need to add 1, maybe 2 unique credit cards to their account/device. Any account/device trying to add 3, 4, 5, or more credit cards to an account should be closely inspected and possibly restricted from adding any more. The stored credit card should also be tied to the device, rather than the account. That way, if an account is taken over from a new device, there will be no stored credit card information available for the fraudster to use. Both of these require a strong and unique identifier on the device level.
Prevention Methods for Consumers
1) Don’t reuse passwords across multiple sites! – This is the single most important piece of advice consumers should follow. If you reuse the same password across multiple sites, it is no longer a question of if, but rather when you will become a victim of Account Takeover and fraud. Using a Password Manager to create strong and unique passwords will greatly improve your personal security posture.
2) Be mindful of the sites and apps that you enter your username and password in to. Many fraudsters are now relying on phishing scam sites that look eerily similar to the real retailer/airline/bank site but are in fact under the control of the fraudster and are meant to harvest credentials in order to commit fraud.
3) Make sure you have a reputable antivirus on your Smartphone and uninstall any apps that are flagged as suspicious or malicious.
4) Use a virtual credit card. Virtual credit cards are now available from a number of organizations. These are beneficial as you can create a single use virtual credit card with a credit limit for a specific retailer. That way if the retailer suffers a data breach, or your account is taken over, your fraud exposure is contained and your real credit card is still secure.
5) Ask the retailer about their security controls and practices, and how they prevent Account Takeover. If they give you a sub-par canned answer, maybe you should think twice before saving your credit card information in their app.
*** This is a Security Bloggers Network syndicated blog from Shape Security Blog authored by Carlos Asuncion. Read the original post at: https://blog.shapesecurity.com/2020/02/13/in-store-payments-via-mobile-apps-can-lead-to-increase-in-card-not-present-cnp-fraud/