In 2025, fraud prevention systems blocked approximately R$ 2,4 billion in losses in Brazilian e-commerce , distributed across 2,3 million attempted frauds, according to Serasa Experian 's Fraud Map . This number illustrates the scale of the risk that accompanies every online sale and explains why anti-fraud measures in e-commerce are no longer a concern only for large operations.
The need for caution becomes even more urgent at the end of the year. During Black Friday 2025, the average value of fraudulent transactions reached R$ 1.504,57, approximately 40% above the annual e-commerce average, according to a survey by Serasa Experian for that period. When the volume of orders increases, so does fraud, with higher values per attempt.
On this page you will find:
Anti-fraud in e-commerce: the points that matter most.
Before we get into the details, here's a summary of what every retailer needs to understand:
- E-commerce fraud It is any attempt to make a purchase using stolen data, cloned cards, or fake identities, which ends in a chargeback and loss for the store;
- The cost falls on the retailer: In most card-not-present purchases, the store is responsible for the refund and also loses the product that has already been shipped;
- The end of the year concentrates the risk: More requests, more pressure for quick approval, and more sophisticated scams, many of them powered by artificial intelligence;
- Not every category faces the same risk: Electronics, fashion, and beauty products are leading the attempts, with high-value items that are easy to resell.
- Anti-fraud measures aren't just about blocking: A good strategy also avoids blocking genuine customers, the so-called false positives, which cost sales and reputation;
- It's possible to prepare: Layers of protection, analysis rules, and monitoring reduce losses without halting operations.
Why Q4 is the most dangerous period
The fourth quarter combines Black Friday, Christmas, and end-of-year shopping in just a few weeks. This is when stores sell the most and, therefore, when they attract the most fraudsters.
The fraudster's logic mirrors that of retail: with many orders coming in at the same time and teams pressured to approve them quickly, a suspicious transaction has a greater chance of going through. According to Serasa Experian , in the first week of November 2025 alone, there were approximately 39 attempted frauds in e-commerce , with the potential for losses of up to R$ 29 million for retailers.
The trend is upward in the medium term. The Online Retail Agenda study , by Koin with Gmattos , projects losses exceeding R$ 8,1 billion in Brazilian e-commerce in 2026 (compared to R$ 7,8 billion in 2025 and R$ 3,9 billion in 2020). The same study indicates a fraud incidence of 4,1% of orders in Latin America, above the approximately 3% in North America and Asia.
Where fraud is most prevalent in e-commerce.
Knowing what the fraudster is looking for helps decide where to strengthen protection. According to Serasa Experian data from 2025, the categories most targeted by volume of attempts were:
- Electronics: 126,3 attempts, with a risk rate of 3,2% and an average fraudulent transaction value of R$ 2.350,94.
- Fashion and clothing: 103,2 attempts.
- Beauty, health and personal care: 95,6 attempts.
The pattern repeats itself: high ticket price, easy resale, and high demand during commercial holidays. But the warning applies to any store; the average ticket price of a fraudulent purchase was R$ 1.057,87 in 2025, almost double the R$ 538,79 of a legitimate purchase . The fraud targets the most expensive order that the operation allows.
What underpins a good anti-fraud strategy in e-commerce?
Effective protection works in layers, not just a single filter. This includes risk analysis of each order, buyer authentication, approval rules based on value and profile, and, in larger transactions, models that learn from transaction history.
The point that many retailers ignore is balance. A good anti-fraud system isn't the one that blocks the most, but rather the one that effectively distinguishes fraudulent transactions from genuine purchases. Blocking legitimate customers (false positives) means lost sales and a customer who is unlikely to return. The Koin/Gmattos study itself links the lowest approval rates in Latin America to these unwarranted blocks.
Therefore, three indicators deserve attention during peak season: the chargeback rate , which measures successful fraud; the approval rate , which shows how many legitimate sales are generated; and the false positive rate , which reveals how many genuine customers are being rejected. Monitoring all three prevents fraud from impacting revenue.
The sophistication of the scams reinforces this need. A survey by Reclame AQUI showed that 63% of Brazilian consumers do not feel capable of recognizing fraud perpetrated with artificial intelligence, such as cloned pages and fake offers.
How to protect your store before the peak in orders.
The best time to adjust your protection is now, before the volume explodes, and a few adjustments can make an immediate difference:
- Review the analysis rules. before the peak season, considering that the average ticket price and the number of orders will increase;
- Work in layers, combining your payment method's anti-fraud solution with your own rules and, if possible, a dedicated tool;
- Closely monitor high-value orders. and the unusual peaks in your store;
- Align yourself with the gateway and the acquirer. Regarding limits, rules, and liability for chargebacks this season;
- Protect the customer's account.Pay attention to suspicious logins and attempts to change registration data.
Anti-fraud measures don't eliminate risk, but they determine how much of it translates into losses. Reaching Q4 with the operation prepared is what separates a season of record sales from a season of chargebacks.
Want to go further?
Preparing your store for the peak order volume at the end of the year involves more than just fraud protection. It's worth checking out other content on the e-Plus blog about checkout, Black Friday, and peak season operations to ensure everything is in order by Q4, from the first visit to payment approval.
Frequently asked questions about anti-fraud measures in e-commerce.
What is anti-fraud in e-commerce?
Anti-fraud in e-commerce is the set of technologies and rules that evaluates each order to identify purchase attempts using stolen data, cloned cards, or fake identities. The goal is to block fraud before the product is shipped, without barring legitimate customers.
Who pays the price for e-commerce fraud?
In most card-not-present purchases, the loss falls on the store. When there is a chargeback due to fraud, the merchant usually has to refund the amount and also loses the product that has already been shipped, in addition to paying fees and charges for the disputed transaction.
Why does fraud increase on Black Friday and at the end of the year?
Because the volume of orders grows and teams are under pressure to approve them quickly, it facilitates the passage of suspicious transactions. On Black Friday 2025, the average fraudulent order value reached R$ 1.504,57, about 40% above the annual average, according to Serasa Experian.
Do small shops also need anti-fraud measures?
Yes. Fraud targets the most expensive order the operation allows, not the size of the store. With an average fraudulent order value close to R$1.057,87 in 2025, even a few chargebacks can significantly impact the cash flow of a small business, making prevention essential at any size.
