Comment on Could someone explain the networking behind transparent proxies and MiTM snooping using certificates to me?

• MigratingtoLemmy@lemmy.world ⁨11⁩ ⁨months⁩ ago

  I see, thanks for the explanation. Amazon sends the certificate to the proxy, and the proxy sends its own certificate, masquerading as amazon, to the user.

  Thanks

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  • canni@lemmy.one ⁨11⁩ ⁨months⁩ ago

    I think it’s important to understand how a typical SSL certificate is generated. Basically, there are a handful of companies that we have all agreeded to trust. When you download Chrome it comes with a set of trusted root certificates, so does your OS, etc. So when Amazon wants to create an SSL for amazon.com, the only way they can do that is by contacting one of those handful of trusted companies and getting them to issue a certificate that’s says Amazon.com. When you go to the site, you see a trusted party generated the cert and your browser is happy.

    When you create a new root certificate and install it on your computer, you become one of those companies. So now, you can intercept traffic, decrypt it, read it, reissue a certificate for amazon.com (the same way Amazon would have gotten one from the third parties), reencrypt it, and pass it along to the client. Because the client trusts you it’s still a valid certificate. But if you inspect the certificate on the client side the root signer will no longer be GoDaddy or whatever, it will be you.

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    • MigratingtoLemmy@lemmy.world ⁨11⁩ ⁨months⁩ ago

      Basically, if I were to run a CA locally (on my network) and use that certificate in some OS, I should be able to set up a MiTM setup easily. Except that applications like web browsers don’t care and will utilise certificate pinning anyway, regardless of which certificates I keep in my certificate store in the OS.

      Also, let’s say I’m running HAProxy/Caddy/NGINX at home which acts as my SSL-termination point for my network. In this case, if a service wants to access the internet, do these reverse proxies encrypt the outbound traffic with a different certificate?

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      • canni@lemmy.one ⁨11⁩ ⁨months⁩ ago

        If I understand the question, the traffic in your local intranet will basically always be encrypted with your root cert. So client -> proxy with your cert, then normal internet encryption from proxy -> internet.

        For the apps, it depends on the app, but you can usually insert your cert into their store, it might just be different than the systems store. This could be hard to do on an non-rooted iPhone, idk. My experience is with Linux desktops. For example, in chromium based apps, there is a database in ~/.pki/nssdb that you can insert your cert into. Again, this is something I do at work where we have a very tightly controlled network and application stack. I would not recommend a MiTM proxy for your home environment, it will only cause headaches.

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  • losttourist@kbin.social ⁨11⁩ ⁨months⁩ ago

    Yes, I think that 'masquerading' is the key bit to grasp. The MITM Proxy isn't just intercepting the traffic, it alters the traffic as it passes through.

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    • MigratingtoLemmy@lemmy.world ⁨11⁩ ⁨months⁩ ago

      Thanks, got it!

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