HttpOnlyevästeitä

HttpOnly cookies are a security feature implemented in web browsers to enhance the protection of sensitive information stored in cookies. These cookies are set by web servers and are not accessible via JavaScript, which helps prevent certain types of cross-site scripting (XSS) attacks. By marking cookies as HttpOnly, the browser ensures that these cookies are only sent to the server and not exposed to client-side scripts, thereby reducing the risk of cookie theft and unauthorized access.

The HttpOnly attribute is added to a cookie by the server when setting the cookie. For example, a server might set a cookie with the HttpOnly attribute using the following HTTP header:

Set-Cookie: sessionId=abc123; HttpOnly

In this example, the sessionId cookie is marked as HttpOnly, meaning it cannot be accessed or modified by JavaScript running on the client side. This restriction helps mitigate the risk of XSS attacks, where an attacker might inject malicious scripts into a web page to steal cookies or perform unauthorized actions.

While HttpOnly cookies provide a layer of security, they are not a complete solution. They should be used in conjunction with other security measures, such as secure (HTTPS) connections, content security policies (CSP), and proper input validation, to ensure comprehensive protection against web-based threats. By incorporating HttpOnly cookies into a broader security strategy, web developers can significantly enhance the security of their applications and protect user data from potential exploits.