Build an Anti-Skimming Detection System for E-Payments

Digital skimming, or Magecart-style attacks, silently steal card information from payment forms by injecting malicious JavaScript into web pages. These attacks often go unnoticed. An anti-skimming system can detect anomalies and alert site owners before damage is done.

This system monitors the e-commerce checkout page in real time or on scheduled scans. It flags unexpected script injections, form field changes, new input listeners, or data exfiltration endpoints that indicate card data theft activity.

The tool scans or embeds JavaScript on the checkout page to monitor changes in real time. When an unauthorized script is added or a new field captures sensitive data unexpectedly, it logs the action and sends alerts. Scheduled backend crawlers can also analyze deployed HTML for known malicious patterns.

• Integrate client-side scanner on checkout or payment pages.
• Track script loading, DOM changes, and new network calls.
• Flag differences from expected HTML structure or known good script sources.
• Send alerts for possible Magecart-style or keylogger activities.
• Optionally block risky actions or remove injected scripts in real time.

• How Magecart Skimming Works
• Using MutationObserver in JavaScript
• Content Security Policy (CSP) Guide
• Puppeteer Crawler for DOM Audits
• Sample Magecart Detector GitHub