Third-party script monitoring tools fall into three categories: Content Security Policies that restrict which scripts can load, crawler-based scanners that check scripts periodically from the outside, and runtime monitors that instrument the browser during real user sessions. CSPs block by origin but cannot inspect what a script does once loaded. Crawlers miss scripts that only activate on checkout pages or for specific visitor segments. cside uses the script tag approach, monitoring behaviour across 100% of real sessions with no sampling, which is why QSAs accept it for PCI DSS 4.0.1 requirements 6.4.3 and 11.6.1 where CSPs and crawlers are often rejected.
How do client-side attacks actually happen?
Compromising a third-party service your website relies on is one common way attackers get in.
Why can't traditional security tools detect client-side threats?
Firewalls, WAFs, and vulnerability scanners are traditional security tools used to protect your server, but they cannot see what's happening in your users' browsers.
What's the difference between client-side security and server-side security?
Server-side security protects your infrastructure, while client-side security focuses on where your application actually runs, inside your users' browsers.
What's the difference between client-side security and application security?
Client-side security is a critical subset of AppSec that focuses on protecting applications where they actually execute--in users' browsers.