How we train AI to uncover malicious JavaScript intent and make web surfing safer

Modern websites rely heavily on JavaScript. Leveraging third-party scripts accelerates web app development, enabling organizations to deploy new features faster without building everything from scratch. However, supply chain attacks targeting third-party JavaScript are no longer just a theoretical concern — they have become a reality, as recent incidents have shown. Given the vast number of scripts and the rapid pace of updates, manually reviewing each one is not a scalable security strategy.

Cloudflare provides automated client-side protection through Page Shield. Until now, Page Shield could scan JavaScript dependencies on a web page, flagging obfuscated script content which also exfiltrates data. However, these are only indirect indicators of compromise or malicious intent. Our original approach didn’t provide clear insights into a script’s specific malicious objectives or the type of attack it was designed to execute.

Taking things a step further, we have developed a new AI model that allows us to detect the exact malicious intent behind each script. This intelligence is now integrated into Page Shield, available to all Page Shield add-on customers. We are starting with three key threat categories: Magecart, crypto mining, and malware.

^{Screenshot of Page Shield dashboard showing results of three types of analysis.}

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