Could someone explain the networking behind transparent proxies and MiTM snooping using certificates to me? (lemmy.world)

submitted 11 months ago by MigratingtoLemmy@lemmy.world to c/selfhosted@lemmy.world

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Hi everyone, I've been trying to understand how MiTM setups like a transparent proxy work.

Obviously, the use-case here is in a personal scope: I'd like to inspect the traffic of some of my machines. I am aware that Squid can be a transparent proxy, and some might use the Burp Suite to analyse network traffic.

Could someone explain the basic networking and the concept of certificates in this scenario? I feel like I don't understand how certificates are used well enough.

For example: I realise that if someone inserts a root certificate in the certificate store of an OS, the machine trusts said CA, thus allowing encrypted traffic from the machine to be decrypted. However, say the machine was trying to access Amazon; won't Amazon have its own certificate? I don't know how I'm confused about such a simple matter. Would really appreciate your help!

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[-] MigratingtoLemmy@lemmy.world 1 points 11 months ago

Shouldn't flushing the cache mitigate this problem?

[-] stifle867@programming.dev 6 points 11 months ago

No, not at all. The request never hits the cache. The certificate is stored within the app and all internet communication is specifically pinned to said certificate. It doesn't even ask your certificate store.

[-] MigratingtoLemmy@lemmy.world 1 points 11 months ago

I see. Thanks, I'll have to rethink the idea in that case.

[-] stifle867@programming.dev 2 points 11 months ago

Yeah, unfortunately it's a huge barrier if you're wanting to see why your devices are phoning home and the data being sent. It makes it extremely difficult if not impossible for most people to bypass.

[-] MigratingtoLemmy@lemmy.world 1 points 11 months ago

I understand. What other methods would you suggest to be able to snoop on/decrypt the traffic from my device?

[-] stifle867@programming.dev 3 points 11 months ago* (last edited 11 months ago)

Specifically for attempting to bypass certificate pinning you're solidly in the realm of reverse engineering. I haven't attempting it myself but I have read the efforts of others over the years and the process was quite evolved and ever changing. If you are interested in going down this rabbit hole you may use these links as starting points but be prepared to adapt them.

https://felipe-herranz.medium.com/uncertify-a-tool-for-recompiling-android-apps-bypassing-different-certificate-pinning-techniques-de3d30ded2c6

https://gist.github.com/approovm/e550374428065ff1ecafca6a0488d384

https://frida.re/

https://codeshare.frida.re/browse

Best of luck.

[-] MigratingtoLemmy@lemmy.world 2 points 11 months ago

Thanks, I had heard of frida before, but never tried it. I'll save this comment, many thanks for the pointers!

this post was submitted on 24 Oct 2023

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