Magecart Plants Card Skimmers via Old Magento Plug-in Flaw

Cybercriminals operating under the Magecart umbrella group are exploiting an old vulnerability in a Magento plugin to insert credit card data-skimming malware on sites built on the ecommerce platform.

In an alert earlier this month, the FBI described the latest attacks as involving CVE-2017-7391, a three-year old—and long since patched—cross-site scripting vulnerability in the Magmi 0.7.22 mass importer for Magento.

According to the FBI, the attackers breached a US Magento e-commerce site via the vulnerable plugin and placed malicious JavaScript code on checkout pages where users submit payment card data and personal information. The attackers also retrieved administrator credentials and downloaded web shells that allowed them to install other malware and maintain a persistent presence on the site.

The malware allowed the attackers to gather payment-card data and other information belonging to cardholders such as their names, email addresses, physical addresses, and phone numbers. The criminals encrypted the stolen data and stored it in a JPEG dump file they had created. They later used the web shell to extract the dump file using HTTP GET requests, the FBI said.

The alert provided indicators of compromise that organizations running Magento could use to protect their site against the Magecart attacks.

Pervasive Threat

Magecart is an umbrella term for a collection of at least seven separate groups that have been placing online card skimmers on hundreds of thousands of e-commerce sites worldwide over the last few years. Some estimates have pegged the number of sites that Magecart actors have comprised at more than two million.

In many cases, the skimmers have been comprised of very small pieces of JavaScript code injected into vulnerable plugins and other third-party components on e-commerce sites. Typically, the malware has worked by capturing payment card data and other PII that users enter into checkout pages and then transmitting the data to remote, attacker-controlled systems.

Hank Schless, senior manager of security solutions at Lookout, says the card-skimming malware Magecart injects into websites can be hard to spot. "Much like a Trojanized version of a legitimate mobile app appearing on an app store or a text supposedly from your bank with a normal-looking URL, malicious actors always look for ways to throw as few red flags as possible," he says. 

With a majority of people working from home and conducting a lot more transactions online than before because of the COVID-19 pandemic, expect bad actors like Magecart to ramp up their malicious activity, Schless says.

"Magecart is a perfect example of threat actors exploiting a changing risk landscape that IT and security teams have been forced to protect against," he says. The environment makes it necessary for organizations to lock down every extension of the corporate network - from payment platforms to employee mobile devices, Schless says.

Alex Guirakhoo, threat research team lead at Digital Shadows, says the surge in online activity as a result of COVID-19 has given attackers a larger attack surface. According to Guirakhoo, cybercriminals in underground forums have been actively discussing ways to take advantage of increased consumer traffic on ecommerce sites to hide their malicious activity.

"To mitigate against code-injection attacks, organizations should ensure that they monitor for any unauthorized code changes, particularly on checkout pages of e-commerce platforms," Guirakhoo notes. "Organizations should also monitor for any publicly disclosed vulnerabilities affecting any of their third-party e-commerce platforms."

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