this post was submitted on 21 May 2024
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It is possible and it has been done.
You need to get your "hacker" key signed/certified by an official CA. Which is not that difficult with some of them because they are doing it for money.
You don't really 'need to' in a world where a good proportion of people will happily click 'continue anyway' when they get any sort of certificate error
Thats why we have HSTS and HSTS preloading, so the browser refuses to allow this (and disabling it is usually alot deeper to find than a simple button to "continue anyways")
In Chromium browsers you can simply type "thisisunsafe" to bypass even HSTS failures.
Not possible without a certificate. There will be no TLS connection, only an error message. No 'click continue'.
It is trivial for an attacker to make self-signed TLS certs, and you can absolutely just click “continue” on sites that use them when you get a warning from the browser
What browser is that?
Firefox, Chrome, Edge, will all warn you about self-signed certs or cert mismatches but allow you to continue. You're completely correct that SSL/TLS needs a certificate, but it doesn't need to be CA issued or in any way legitimate for the encrypted tunnel to be established
I am personally using firefox and referencing my own servers that use their own self-signed TLS certs that I have not bothered to load onto my pc because they aren’t public, but chromium-based browsers aren’t some outlier here
Your own servers probably also dont have HSTS enabled, or clicking continue will be disabled (if not overwritten in your browser-config)
Reading the HSTS spec, it doesn’t work on first connection, and while most people are using websites they access more than once, that notably isn’t all web use.
Indeed, not classically, but there are HSTS preload lists you can put your domain into which will be downloaded by supported browsers.
And via HSTS you can include all your subdomains, which would then force proper TLS connections for those you havent visited before too.
With the new TLS1.3 version we are getting the HTTPS / "SVCB" Record which not only allows ECH but also indicates to the client similar protection policies like HSTS. (RFC 9460)
ECH will then make such attacks impossible on TLS-level, assuming DNSSEC is used and client can make an integrity-checked lookup e.g. via DoH/DoT or validating DnsSec themselves.
The strength of this depends on the security-chain you want to follow of course. You dont need DNSSEC, but then the only integrity-check is between DNS-Service and Client if they use DoH/DoT (which is usually enough to defeat local attackers)
It would be inherently impossible for HSTS to work on first connection, you are correct.