Cross-site scripting, or XSS, is an attack where a hacker injects malicious code, usually JavaScript, into a webpage that other users then load and run. The injected script executes inside the browser of each visitor with the same trust level as the real site.
An attacker finds a spot on a website that accepts user input and displays it back without properly cleaning it, such as a comment field or search box. The attacker submits input containing a script tag instead of normal text. When another user views that page, the browser runs the injected script as if the script were part of the trusted site. The script can then steal cookies, log keystrokes, or redirect the user to a fake login page.
Match the strength of this control to what is actually at risk in the workflow.
USER-country-de-session-task01The credential string is the only configuration needed -- "country-de" sets the exit, "session-task01" keeps it consistent, and cross-site scripting is handled by the gateway rather than your application code.
Test the setup with a leak-test tool or packet capture to confirm this protection is actually working, not just configured.
Pair this with sane session handling and header hygiene -- no single control covers a full workflow on its own.
Apply the strongest version of this control to logins, payments, and personal data -- it is overkill for public information.
Do not let two workflows that need to stay separate for privacy or account reasons share the same session or IP.
An attacker posts a comment containing hidden script code on a forum, and every visitor who views that comment unknowingly runs the script.
XSS remains one of the most common web attacks because so many sites accept user input. Strong input validation and a solid Content Security Policy are key defenses against it.
Stored XSS saves the malicious script on the server, so it runs for every visitor who loads that page. Reflected XSS only runs when a victim clicks a specially crafted link.
Developers sanitize and escape all user input before displaying it. They also use a Content Security Policy to limit which scripts can run.
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