What Are the Risks of Third-Party Scripts on Your Website?
Every third-party script on your website runs with the same access as your own code: it can read the page, read what visitors type and send data anywhere. This video covers why the set of scripts on a page is a tree rather than a list (vendors load vendors), where shadow code comes from, the six kinds of client-side attack (card skimming, credential harvesting, data leakage, malicious redirects, cryptojacking, clickjacking and overlays), why a WAF, SIEM and EDR don't see any of it, and the four things to monitor for every script: identity, integrity, behaviour and change over time. On payment pages, PCI DSS 6.4.3 & 11.6.1 have made this mandatory since 2025.
Full answer: Third-Party Script Monitoring and Management
Transcript
The main risk of third-party scripts is that every one of them runs with the same access as your own code. It can read the page, read what visitors type, and send data anywhere, and the browser can't tell it apart from your checkout. We make Script Monitoring. It records every script that runs on your pages, in every real session, from one tag. There's no privilege boundary on a page. Your checkout code can read the card field. So can the analytics tag. So can the script that analytics tag loaded. And the scripts on your page are a tree, not a list. You approve a vendor, and the vendor loads two more. The last script in the chain is often a company you've never heard of. Approving a vendor isn't approving a script. Then there's shadow code: scripts nobody on the current team approved. A campaign tag nobody removed. A tag added by someone who has left. A plugin that ships its own scripts. So what can go wrong? Card skimming. Credential harvesting on a login form. Data leaking to third parties, usually a misconfiguration. Malicious redirects for a slice of traffic. Cryptojacking. And overlays drawn over the real interface. Your existing tools don't see it. A WAF, a SIEM and EDR all watch infrastructure you own. A skimmer posts the card from the browser straight to the attacker, so none of that traffic reaches you. And it's a moving target. The same URL can serve different code by browser, device or location. So monitor four things for every script. Where it loaded from and what loaded it. Whether its contents match what you approved. What it does, like reading form fields or sending data. And when any of that changed. Build the inventory from real sessions, not your tag manager. Delete what nobody can justify. Then review what changed, each week. On payment pages, PCI DSS 6.4.3 & 11.6.1 require this since 2025. Script Monitoring is free for 1,000 page views a month, with unlimited scripts and vendors. Pro starts at $99 a month, with a 14-day trial. Start for free at scriptmonitoring.com.