Intermediate LevelWeb Security & Cyber Defense
What is the HSTS Preload List and how do you submit a domain for hardcoded browser HTTPS?
❓ Interview Prompt: Explain HSTS Preloading, hstspreload.org submission, hardcoded browser source code lists, and zero-visit HTTPS guarantees.
Standard HSTS leaves a small vulnerability window during a user's very first visit to a domain before the HSTS header has been received:
HSTS Preload List Solution:
A global list maintained by Chrome and integrated into all major browsers (Firefox, Safari, Edge):
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Submit domain at 'hstspreload.org' with header 'Strict-Transport-Security: max-age=63072000; includeSubDomains; preload'.
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Browser bakes domain into source code; even the initial first visit is forced to HTTPS locally!
Code Implementation Example
http
HTTP/1.1 200 OK
Strict-Transport-Security: max-age=63072000; includeSubDomains; preload💡HSTS header configured for HSTS Preload List submission.
🎯 Interview Key Takeaway
Submit domains to the HSTS Preload List to ensure even the initial first visit is automatically upgraded to HTTPS.
#HSTS Preload#HTTPS#Browser Security#Intermediate
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