How Fraudsters Are Using Test Credit Card Numbers

If you run an e-commerce store, chances are you've already encountered some form of fraud. But one sneaky tactic that often flies under the radar is credit card testing. This technique is used by fraudsters to validate stolen card details before making bigger purchases.

You might notice unusual, small-dollar transactions or failed payment attempts piling up. It’s easy to write these off as glitches…but they could also be signs of someone using test credit card numbers to probe your checkout system.

Understanding how testing credit card numbers works is the first step to stopping it. In this post, we’ll dive into what credit card testing numbers are, how scammers use them, and what you can do to prevent this type of attack before it snowballs into something much bigger.

What is a Test Credit Card Number?

Before we dive into the risks of credit card testing fraud, it’s important to understand that not all credit card testing is malicious. There’s a key difference between legitimate test credit card numbers used for business purposes and the illegal act of testing stolen credit card data. Here’s how to tell them apart:

Legitimate Use: Test Credit Card Numbers

These are non-functional credit card numbers provided by payment processors or gateways (like Stripe or PayPal) strictly for testing purposes. Developers and QA teams use these to safely test payment systems, simulate transactions, and ensure checkout flows work correctly.

• No real account attached: They aren’t linked to actual bank accounts or cardholders.
• Safe and legal: This is a standard, authorized practice in the e-commerce and fintech space.

Fraudulent Activity: Testing Stolen Credit Card Numbers

This is when scammers use real stolen credit card numbers to make small purchases or attempts, just to check if the card is active. Once verified, the card can be used for more expensive purchases or resold on the dark web.

• Often undetected: These transactions are typically low in value to avoid suspicion.
• Illegal and harmful: This practice is a form of credit card fraud, and it can lead to financial losses for your business.

Why Criminals Test Credit Card Numbers

Criminals test card numbers to separate usable stolen data from junk and scale profitable fraud quickly:

• Buy bulk card data: They obtain large lists of stolen numbers, but many are expired or canceled.
• Automate testing with bots: Botnets run thousands of small transactions to see which cards still work.
• Run low-cost purchases: Tiny buys minimize detection while verifying a card.
• Harvest the winners: Working cards are saved for higher-value fraud.
• Cash out remotely: Criminals use virtual gift cards, reship addresses, or porch pirates/mules to collect goods without being near the victim.

In short, credit card testing numbers offer a low-risk and quick way to find cards to fuel larger fraud.

The Nuances of E-Commerce Credit Card Fraud

When people think of credit card fraud, they often think of the simplest method: A thief using a stolen credit card to make a purchase.

The transaction usually goes through, and the victim has to file a complaint with their card issuer to rectify the situation. The items purchased may be gift cards that the criminal uses as cash, goods that are resold, or goods that are kept by the criminal.

This type of crime has been around since credit cards were first issued, and it continues to be a problem as online sales platforms make it harder to check identification before a purchase is made.

Credit card fraud can be broken down into two broad categories:

1. Card Not Present (CNP)

This is where the fraudster completes a transaction online or over the phone using stolen card information.

It’s estimated that roughly 70% of all card-related fraud happens in a card-not-present scenario. And CNP fraud is projected to reach $49 billion, globally, by 2030.

This can be explained by the increased ease and safety of card not present fraud for scammers. With “card present” fraud, the person using the stolen card could be caught by security or police if a card was reported stolen, their likeness captured by CCTV cameras, and their general location tracked to the site of the fraud attempt.

“Card not present” fraud lets them use the card without the risk of getting physically caught at the time of transaction, increasing the likelihood of getting away.

Affiliate Marketing Fraud

This method doesn’t rely so much on the actual goods purchased. Instead, the payday comes in the form of an affiliate payment. This lets the fraudster double-dip on their money-making schemes.

Since affiliate marketing often pays a percentage of a sale, fraudsters have learned that they can use this as a way to cash in. By making fraudulent purchases with stolen payment card information, they can get paid by the affiliate—typically before the chargeback comes through.

The charge is often still disputed, but that isn’t the scammer’s concern in this case. The money they collect from the marketing firm is what they are interested in.

This form of fraud could be another driving factor behind the increase in “card not present” fraud.

2. Card Present Fraud

As the name implies, this is where the fraudster visits a store location with a copy of a card or even the actual stolen credit card.

However, this type of fraud has been steadily declining due to advancements in payment technology, particularly the widespread adoption of:

• EMV chip cards: These are far harder to clone than traditional magnetic stripe cards.
• Contactless payments: Mobile wallets and tap-to-pay systems add an extra layer of encryption and device authentication.
• Improved in-store security: Many retailers have upgraded their point-of-sale (POS) systems and now require chip or contactless verification, reducing the effectiveness of stolen or cloned cards.

How One Fraudulent Transaction Creates Multiple Victims

A fraudster running a credit card numbers test does more than simply impact the unlucky cardholder. Even a single instance of credit card testing fraud can harm multiple parties:

1. The Cardholder: May face temporary overdrafts or blocked accounts while disputing the unauthorized charge.
2. The Merchant: Loses revenue, product, shipping costs, and often gets hit with chargeback fees—all while being held liable for the fraud.
3. The Bank or Card Issuer: May have to reimburse the customer, absorb the cost if the merchant isn’t liable, and handle fraud reports and paperwork

How Crooks Collect and Test Credit Card Numbers

The sad fact is that there is no shortage of methods by which fraudsters can scam people out of sensitive financial information.

This isn’t limited to payment card information like the 16-digit number, CVV, and expiration date either. Some scammers might collect a victim’s bank account information to make direct money transfers using that account number.

Here are a few ways that fraudsters might illicitly collect financial information:

1. Buying Stolen Payment Card Info off the Dark Web

Some criminals don’t use stolen credit card information themselves. Instead, they auction that information off to the highest bidder or batch large collections of stolen card data together to sell en masse to another fraudster.

The value of stolen payment card data varies wildly. Some estimates range from $5 per card to $150 per card, depending on the quality and amount of supplemental data that goes with it.

2. Credit Card Skimmers

One of the oldest tricks in the book for collecting credit card information is to use a card skimmer on a point-of-sale (POS) terminal in a retail location.

Here, a thief will take advantage of an understaffed store to take apart a credit card reader and insert a skimmer device.

The device resides in the card reader and will scan the information off of any card inserted into the scanner afterwards. Some card skimmers may also include a fake keypad placed over the real one to capture debit card information as well. The information is stored on the skimmer until the thief can retrieve it.

Card skimmers are especially common in gas station pumps, as they are located outside where store staff are less able to directly monitor them and intervene. A particularly busy gas station could allow criminals to collect hundreds (or even thousands) of card numbers in a relatively short period of time.

3. Online Phishing Schemes

Cybercriminals (crooks who operate online) may use a technique called phishing to trick people into voluntarily giving up their credit card or banking information in droves.

There are a lot of different phishing techniques, but they often involve using spoofed email and website domains to trick their victims into thinking that they’re dealing with a legitimate company.

For example, a fraudster might send out a mass email to random people online, warning them that their Netflix account payment information is invalid and needs to be updated. In the email, there’s a link to a “mynetflix.payment.com” page (or something similar) that looks like the streaming service’s accounts page.

Unsuspecting users then re-enter their credit card info to avoid losing their streaming service, only to get hit with a bunch of fraudulent charges a week or two later.

4. Massive Data Breaches

Data breaches are a way for fraudsters to acquire a massive quantity of credit card numbers in a short amount of time.

Once a company’s security has been breached, cybercriminals can start collecting data—whether it’s stored data on the company’s database or “data-in-flight” that is captured as transactions are made.

Some of the worst data breaches have involved the theft of account details for millions of people, taking place over several years. In 2024, a massive data breach of National Public Data allegedly exposed up to 2.9 billion records with highly sensitive personal data of up to 170M people in the US, UK, and Canada.

How to Stop Test Credit Card Fraud

While big purchases are where the criminals make most of their money, testing credit card numbers tends to hurt businesses the most.

These small purchases often end up costing hundreds after you are hit with chargeback fees and other problems. These purchases are also easier to spot, if you know what operational trends to look for:

• Monitor small order activity. If you notice that you are receiving a large volume of small order attempts, there may be something underhanded going on.
• Watch for purchases of small items that often accompany larger ones or items that are purchased out of season.
• Monitor purchases that come from foreign IP addresses, especially if you sell primarily inside your own country and you see a wave of traffic from customers abroad.

The most effective method of preventing credit card fraud on your site is to use a fraud prevention solution. If you place this type of solution in your security stack, it will monitor for possible fraud.

By collecting hundreds of data points, the best-in-class fraud prevention solutions spot and stop fraudulent activity without blocking legitimate customers from making a purchase.

Whether it is full credit card fraud or simply testing credit card numbers, many e-commerce sites are going to face this issue at one time or another.

Before your business is hit by fraudsters, look into how a trusted fraud prevention solution can help you. The costs associated with credit card fraud will continue to rise as the criminals become more and more sophisticated.

Make sure that you are doing what you can to protect your business and your customers by employing the right solutions to fight back against fraud.

Experience the power of Anura and discover just how much fraud you have with a free trial!