HSTS

What is HSTS?

HTTP Strict Transport Security (HSTS) is a crucial web security policy that helps protect websites from certain types of attacks, specifically protocol downgrade attacks and cookie hijacking. Introduced by the Internet Engineering Task Force (IETF) as RFC 6797, HSTS allows web servers to declare that web browsers (or other complying user agents) should only interact with it using a secure HTTPS connection, and never via the insecure HTTP protocol. This dramatically reduces the risk of man-in-the-middle (MITM) attacks where an attacker might try to intercept traffic over an unencrypted connection.

How HSTS Works

When a user first visits an HSTS-enabled website over HTTPS, the server sends a special Strict-Transport-Security HTTP response header. This header tells the browser to automatically convert all future requests for that domain from HTTP to HTTPS for a specified period (defined by the max-age directive in the header, usually in seconds). Additionally, it instructs the browser to report any certificate errors as fatal, preventing users from bypassing warnings. The includeSubDomains directive can extend this policy to all subdomains as well. For initial visits, where a user might type example.com directly, an HSTS preload list maintained by browsers helps to enforce HSTS even before the first secure connection is made.

HSTS in Security Research

Security researchers often analyze HSTS implementations to gauge a website's overall security posture. Misconfigurations, such as a short max-age or missing includeSubDomains, can leave parts of a site vulnerable. Researchers also look for instances where HSTS is not applied to critical subdomains or where the initial redirect from HTTP to HTTPS is vulnerable. The proper implementation of HSTS is a strong indicator of a website's commitment to user data protection, making its absence or faulty configuration a potential security concern worth investigating.

Using Zondex to Find HSTS

Zondex, a cybersecurity search engine, can be invaluable for identifying HSTS implementations across the internet. By querying specific HTTP headers, researchers can discover which websites have adopted HSTS and analyze the parameters of their policies. This allows for large-scale analysis of HSTS adoption rates and potential misconfigurations.

Here are some example Zondex queries: * http.headers.strict_transport_security:* - Finds all hosts that include the HSTS header. * http.headers.strict_transport_security.max_age:<31536000 - Identifies hosts with an HSTS max-age less than one year (31536000 seconds), potentially indicating a weaker policy. * http.headers.strict_transport_security:"includeSubDomains" - Locates hosts that apply HSTS to all their subdomains. * domain:example.com http.headers.strict_transport_security:* - Checks for HSTS implementation on a specific domain.

Key Takeaways

• HSTS enforces secure HTTPS connections, mitigating downgrade attacks and cookie hijacking.
• It works by instructing browsers via a Strict-Transport-Security header to only use HTTPS for a defined period.
• Security research often focuses on HSTS configuration to assess a website's security posture.
• Zondex provides powerful queries to discover and analyze HSTS implementations globally, aiding in security audits and research.