A security headers scan is a process of evaluating and checking the HTTP response headers of a web application or website to assess its security posture. Security headers play a crucial role in protecting web applications from various types of attacks and vulnerabilities. Here are some common security headers that are often checked during a security headers scan:

Content Security Policy (CSP): CSP headers help prevent cross-site scripting (XSS) attacks by specifying which sources of content are allowed to be loaded by a web page. It restricts the execution of inline scripts and unauthorized content.

X-Content-Type-Options: This header prevents browsers from interpreting files as a different MIME type than what is declared by the server. It helps mitigate MIME sniffing attacks.

X-Frame-Options: This header prevents your web page from being displayed within an iframe on another site, helping to prevent clickjacking attacks.

X-XSS-Protection: It enables the browser's built-in XSS filter, which can help mitigate certain types of cross-site scripting attacks.

Strict-Transport-Security (HSTS): HSTS headers instruct the browser to only connect to the website over HTTPS, reducing the risk of man-in-the-middle attacks.

Referrer-Policy: This header controls how much information is included in the HTTP Referer header when navigating from one page to another. It can help protect user privacy.

HTTP Public Key Pinning (HPKP): Although deprecated, HPKP headers used to help prevent man-in-the-middle attacks by specifying which public keys are valid for a website.

Feature-Policy: This header allows you to control which web platform features are allowed or disallowed on your web pages. It helps prevent unauthorized access to certain APIs.

Server Header: While not a security feature itself, it's a good practice to limit the information disclosed in the Server header to reduce the risk of attackers identifying vulnerabilities in specific server software versions.

Permissions-Policy: This header controls which browser features and APIs can be used on your site, enhancing security by limiting access to potentially sensitive functionality.

To perform a security headers scan, you can use various online tools and security scanners that analyze the HTTP response headers of your website. These tools will provide you with a report on the presence and configuration of these security headers, helping you identify and address any security weaknesses in your web application. It's essential to configure these headers correctly to enhance the security of your website and protect it from common web vulnerabilities.