What is CSP?
A Content Security Policy (CSP) is a security feature used to help protect websites and web apps from clickjacking, cross-site scripting (XSS), and other malicious code injection attacks. At the most basic level, a CSP is a set of rules that restricts or green lights what content loads onto your website. It is a widely-supported security standard recommended to anyone who operates a website.
Using a Content Security Policy adds a layer of protection to your website by defining what sources of content are allowed to load on a page. These rules help to defend against code injections and cross-site-scripting (XSS) attacks, two of OWASP’s top 10 Web Application Security Risks.
XSS attacks happen when an attacker is able to compromise an unprotected website by injecting malicious code. When a user tries to interact with the site, the malicious script executes in the user’s browser, giving the attacker access to the victim’s interactions with the site, like login information etc.
To further enhance security, servers can whitelist domains and specify allowed protocols, such as requiring browsers to use HTTPS. A robust data transfer protection policy includes implementing HTTPS, securing cookies with a secure attribute, and auto-redirecting HTTP pages to HTTPS. Utilizing HTTP Strict-Transport-Security headers further ensures encrypted browser connections. These measures help prevent packet sniffing and maintain secure data transfers.
In addition to these security benefits, a CSP can also help improve the overall performance of your website by reducing the amount of benign (or malicious) content that’s loaded on your page.