How to configure Content Security Policy (CSP) to protect web applications against XSS attacks directly in the browser?
Content Security Policy is a powerful security tool that allows website owners and developers to explicitly specify to the browser which content sources are trusted for loading on a page. CSP configuration is implemented via a special HTTP header that the server sends along with the web page. This header instructs the browser which domains are allowed to run scripts and which requests should be blocked immediately.
The main task of this policy is to prevent cross-site scripting attacks by prohibiting the execution of malicious code injected by attackers. The browser strictly analyzes each page element for compliance with the specified security rules. If a script or image attempts to load from an external unauthorized resource, the browser aborts this action and logs the violation in the developer console.
To implement basic security, resource administrators are advised to follow a specific sequence of actions.