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

• stifle867@programming.dev ⁨1⁩ ⁨year⁩ ago

  There are some cases where this would not work by the way. It’s called certificate pinning and it’s basically when an application comes with the trusted certificate for a host built-in. Even if you were to override it with a root certificate in the certificate store, the app simply wouldn’t use it.

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  • MigratingtoLemmy@lemmy.world ⁨1⁩ ⁨year⁩ ago

    Shouldn’t flushing the cache mitigate this problem?

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    • stifle867@programming.dev ⁨1⁩ ⁨year⁩ 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.

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      • MigratingtoLemmy@lemmy.world ⁨1⁩ ⁨year⁩ ago

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

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• ShellMonkey@lemmy.socdojo.com ⁨1⁩ ⁨year⁩ ago

  That’s the sum of it. Like others and I have noted some mobile apps (and Apple phones in particular have their entire OS configured to not trust any intercepted certs when attempting to speak to Apple home base) are prone to using certificate pinning and will reject the intercepted certs regardless of the trust store. It’s mostly beneficial for adjusting the browser.

  If I might ask, what’s the purpose of this proxy? Functionally there are a lot simpler and more efficient ways to block traffic from a phone. If it’s more for traffic inspection I’ve seen a couple VPN based pcap apps for Android that could get a lot more detail while a DNS filter could both control and give visibility to traffic from the device without all the cert hassles.

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  • MigratingtoLemmy@lemmy.world ⁨1⁩ ⁨year⁩ ago

    Thanks, I didn’t realise that certificate pinning was this strict.

    This effort is to check if my mobile has a baseband processor that might be communicating with the internet. I want to know if my device has a backdoor in hardware. The idea with a VPN has me intrigued, could you tell me more about that?

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    • ShellMonkey@lemmy.socdojo.com ⁨1⁩ ⁨year⁩ ago

      play.google.com/store/apps/details?id=app.greyshi…

      Something like that should ship all traffic through a local VPN adapter and output a standard pcap file.

      Another option if you have a bit more fancy networking available is to set up a security onion instance, then mirror a port on the network and just capture everything at an on-wire level. That would also cover things beyond just web traffic to catch other things like ssh or whatever other remote connectivity could be in play. Seeing the content of the connection is different than just seeing the connections existence though. The endpoint generally has the best visibility before data gets pushed into a a connection but unless you start getting into kernel level debugging it can still be hard to see into the behavior of internal applications.

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      • MigratingtoLemmy@lemmy.world ⁨1⁩ ⁨year⁩ ago

        Hi, thanks for the resources. However, I don’t think I’ll be able to decrypt the traffic from my mobile using this, yes? Using a VPN for this is a great idea though, this also happens to be how NoRoot firewalls work on Android

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