SecurityHeaders é uma ferramenta que realiza um simples, mas importante, scanner de segurança, tendo como foco os headers http do seu webserver.
Vejam, abaixo, o resultado de um scan realizado em uma URL, onde o webserver não possui as implementações de segurança adequadas:
MISSING Strict-Transport-Security: HTTP Strict Transport Security is an excellent feature to support on your site and strengthens your implementation of TLS by getting the User Agent to enforce the use of HTTPS. Recommended value “strict-transport-security: max-age=31536000; includeSubdomains”. Read more.
MISSING Content-Security-Policy: Content Security Policy is an effective measure to protect your site from XSS attacks. By whitelisting sources of approved content, you can prevent the browser from loading malicious assets. Read more.
MISSING Public-Key-Pins: HTTP Public Key Pinning protects your site from MiTM attacks using rogue X.509 certificates. By whitelisting only the identities that the browser should trust, your users are protected in the event a certificate authority is compromised. Read more.
MISSING X-Frame-Options: The X-Frame-Options header tells the browser whether you want to allow your site to be framed or not. By preventing a browser from framing your site your can defend against attacks like clickjacking. Recommended value “x-frame-options: SAMEORIGIN”. Read more.
MISSING X-Xss-Protection: The X-XSS-Protection header sets the configuration for the cross-site scripting filter built into most browsers. Recommended value “X-XSS-Protection: 1; mode=block”. Read more.
MISSING X-Content-Type-Options: The X-Content-Type-Options headers stops a browser from trying to MIME-sniff the content type and forces it to stick with the declared content-type. This helps to reduce the danger of drive-by downloads. Recommended value “X-Content-Type-Options: nosniff”. Read more.
O bacana que ele encontra o erro e aponta a correção..