What ecommerce malware actually does
Ecommerce malware rarely announces itself with a broken checkout or a slow page. It usually looks like nothing at all. A payment skimmer sits quietly inside a checkout page and copies card data as customers type it. A server-side backdoor gives an attacker a way back into the store weeks after the original break-in. Both types of attack are designed to run undetected for as long as possible, because every extra day of silent access means more stolen payment data.
This attack family is commonly called Magecart, named after the group that popularized card skimming on Magento stores. The term has since broadened to cover any digital skimming attack, regardless of platform. Security researchers, including the team at Sansec, have tracked this activity since 2015 and describe two broad categories: browser-side skimmers that inject malicious JavaScript into the checkout page, and server-side malware that hides in files, database tables, or scheduled tasks on the hosting environment itself.
Why Magento and Adobe Commerce carry the largest share of risk
Magento and Adobe Commerce are open-source platforms with a large, mature extension ecosystem. That ecosystem is also the primary attack surface. A vulnerable third-party extension, an outdated core installation, or a compromised extension vendor can each give attackers an entry point. Sansec's research has documented several incidents that illustrate the pattern. CosmicSting (CVE-2024-34102) was a critical XXE vulnerability that, according to Sansec's tracking, led to roughly 5 percent of Adobe Commerce and Magento stores carrying a payment skimmer within weeks of disclosure. SessionReaper (CVE-2025-54236) followed a similar path. Sansec reported that 81 percent of Magento stores had been probed for the vulnerability within three weeks of it becoming public, even though a patch was already available.
Sansec also uncovered a supply-chain compromise in 2022, when the distribution server of Magento extension vendor FishPig was breached and used to inject a remote access trojan into every store that installed or updated the affected extension. Incidents like this show that the risk extends beyond your own code. It includes every extension vendor your store depends on.
Platforms with a smaller or more tightly controlled extension ecosystem, such as Shopify, see fewer incidents of this specific kind, largely because the platform vendor controls more of the stack. That difference in architecture, not platform quality, explains most of the gap in reported attacks.
How detection tools like Sansec actually work
Most ecommerce security discussions focus on the browser, because that is where a customer would notice something wrong. Sansec's own research argues that a large share of ecommerce malware hides on the server instead, in places a standard external security scan cannot see. Its scanner, eComscan, runs directly on the hosting server and inspects files, database content, and scheduled tasks for known malware signatures, unauthorized admin accounts, and vulnerable extension versions. It supports Magento, Adobe Commerce, Shopware, WooCommerce, PrestaShop, and OpenCart.
Sansec's second product, Sansec Shield, works differently. It is a Magento-aware web application firewall that blocks known attack patterns in real time, functioning as a layer of protection while a store waits for an official patch. It runs alongside general-purpose firewalls like Cloudflare rather than replacing them, since a generic firewall has no visibility into Magento-specific attack patterns.
Sansec is also a listed malware intelligence partner of VirusTotal and worked with Europol on a cross-border skimming investigation in January 2024 that notified 443 online merchants of compromised customer payment data. That kind of threat intelligence feeds directly into how quickly a scanning tool can recognize a new attack pattern.
Where this fits into PCI DSS and daily operations
PCI DSS version 4.0 added two requirements, 6.4.3 and 11.6.1, that specifically target payment-page tampering and unauthorized script changes. Both became mandatory in March 2025. Server-side malware scanning supports the underlying anti-malware requirement in PCI DSS, while browser-side script monitoring, sometimes called CSP monitoring, addresses the newer requirements more directly. Neither approach covers everything on its own, which is why most serious ecommerce security setups combine a server-side scanner, a web application firewall, and some form of client-side script monitoring.
Patch discipline still matters more than any single tool. Sansec's own numbers on SessionReaper show that even after an emergency patch was released, most stores stayed exposed for weeks. A scanner or firewall buys time. It does not remove the need to patch.
Evaluating a security monitoring vendor
Not every ecommerce security vendor covers the same threat model, so it helps to ask specific questions before committing to one. Ask whether detection runs server-side, browser-side, or both, since each catches different attack types. Ask which platforms are supported natively, because a tool built for Magento will not necessarily understand Shopware's architecture. Ask how often threat signatures are updated, and whether the vendor publishes its own research, since public disclosures are a reasonable proxy for how seriously a vendor treats the threat. Sansec, for example, publishes named vulnerability research such as CosmicSting, SessionReaper, and CronRAT, rather than only marketing claims, which gives you something concrete to verify.
Building a realistic response plan
A response plan should exist before an incident happens, not during one. At minimum, that means knowing who has admin access to the store, keeping the extension list current, and having a documented process for what happens when a scanner flags something. Nordic Web Team treats this as part of the surrounding delivery work around any Magento or Shopware project. Platform choice, hosting, and integration work through cloud infrastructure all shape how exposed a store actually is, and security monitoring should be planned alongside those decisions rather than added afterward.