Secure Cookie Configuration

Cookies are a primary mechanism for maintaining user sessions and storing authentication tokens in web applications. Insecure cookie configuration is a common vulnerability that can lead to session hijacking, cross-site request forgery, and information disclosure. Proper cookie configuration requires setting multiple security attributes that control how, when, and where cookies are transmitted.

The critical security attributes for cookies include: Secure, which ensures the cookie is only sent over HTTPS connections; HttpOnly, which prevents JavaScript access to the cookie, mitigating XSS-based session theft; SameSite, which controls cross-origin cookie behavior to prevent CSRF attacks; Domain and Path, which limit the scope of cookie transmission; and Max-Age/Expires, which controls cookie lifetime. Each attribute addresses a specific attack vector.

Beyond individual flag settings, secure cookie configuration involves using cookie prefixes (__Host- and __Secure-) that enforce additional browser-level constraints, keeping cookie payloads minimal (storing only a session ID rather than sensitive data), signing cookies with HMAC to detect tampering, and implementing proper session lifecycle management including secure generation, timeout, rotation on privilege changes, and complete invalidation on logout.