Sites hacked with credit card stealers undetected for months

Threat actors are gearing up for the holidays with credit card skimming attacks remaining undetected for months as payment information is stolen from customers.

Magecart skimming is an attack that involves the injection of malicious JavaScript code on a target website, which runs when the visitor is at the checkout page.

The code can steal payment details such as credit card number, holder name, addresses, and CVV, and send them to the actor.

Threat actors may then use this information for purchasing goods online or sold to other actors on underground forums and dark web marketplaces known as "carding" sites.

The SCUF connection

In October 2021, Akamai researchers discovered a Magecart attack on SCUF Gaming International, a leading manufacturer of custom PC and console controllers, which resulted in the compromise of the financial details of 32,000 people.

By investigating deeper, the analysts found that the same actor responsible for the attack against SCUF was operating an extensive network of skimmers that stole credit card details from several sites.

These are:

• whitemountainshoes.com – Shoes and footwear (Alexa rank: 425k)
• goldboutique.com – Jewelry (Alexa rank: 1.4 M)
• nafnaf.com – Fashion apparel (Alexa rank: 85k)
• schlafstaette.de – Sleep products
• proaudiostar.com – Professional audio equipment (Alexa rank: 150k)
• truebrands.com – Professional beverage accessories (Alexa rank: 113k)
• loudmouth.com – Clothing and special apparel (Alexa rank: 1.2 M)

The smaller the Alexa rank number, the more traffic that website receives, so the longer the skimmer stays undetected, the more credit card details Magecart actors steal.

As such, actors limit the activity on their scripts to only valuable pages to keep their skimmers hidden on infected sites, making Akamai's investigation harder.

"We found that the skimmer's command and control (C2) server responds with clean code when running on non-sensitive pages...," explains Akamai's report.

"…and (the skimmer) only sends the malicious code if it runs on checkout pages, where credit card information can be found."

Another anti-detection technique followed by Magecart actors is registering a new skimming domain for each targeted website.

If their skimming operation is exposed/discovered, they deactivate that domain and continue the malicious activities on the other sites.

In this particular case, the actors used the same C2 domain for four websites, so a small cluster was unveiled almost at once.

Vigilance advised during Christmas

Consumers who indulge in online shopping are advised to be extra cautious during Christmas when Magecart actors increase their efforts.

Detecting skimmers is the responsibility of e-commerce site owners, not their visitors, so the latter can instead do the following:

• Use an up to date internet security solution
• Prefer paying with electronic methods instead of cards
• Use one-time "virtual" card solutions
• Pay with cash on delivery if possible

If you have bought anything using your credit card from the seven websites listed above this year, consider your payment details compromised and call your bank to request a card replacement.