Post AayCTAxfb7Md7AMjUu by apreiml@fosstodon.org
(DIR) More posts by apreiml@fosstodon.org
(DIR) Post #AayAXLhrOFXHgophx2 by apreiml@fosstodon.org
2023-10-20T17:57:32Z
1 likes, 1 repeats
Well done incident report:"Encrypted traffic interception on targeting the largest Russian XMPP (Jabber) messaging service"https://notes.valdikss.org.ru/jabber.ru-mitm/TLS alone might not always be enough. My takeoff is to take a closer look at certificate transparency monitoring.
(DIR) Post #AayAXOe4SnHsnw5Dxg by apreiml@fosstodon.org
2023-10-20T18:07:29Z
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But I wonder. I if has been the companies itself, they could've just extract the private key from the VPS.
(DIR) Post #AayAk6nC9QnlCQPdaK by lanodan@queer.hacktivis.me
2023-10-20T18:20:57.653810Z
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@apreiml That said aren't most XMPP clients ignoring certificate transparency, meaning that if they would distribute an MITM certificate only to few people it might not be visible?
(DIR) Post #AayCTAxfb7Md7AMjUu by apreiml@fosstodon.org
2023-10-20T18:31:46Z
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@lanodan Monitoring certificate transparency is something the owners of the services need to do. The log lists only which certificates have been issued when. The owner has the knowledge of authentic certificates and can check, if there aren't any additional certificates issued..As a client you can't differentiate between a forged and a valid one, in this case.
(DIR) Post #AayCTDyqND5MTfwDFA by lanodan@queer.hacktivis.me
2023-10-20T18:40:17.870421Z
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@apreiml It's a case of both.Clients should verify that the certificate is part of certificate transparency, for example via OCSP.This needs to exists to make sure that there is no blind spot, which IMHO is what makes Certificate Transparency actually work rather than be snake oil.The admin of course should still check CT logs.
(DIR) Post #AayDp8hilpv8RGwVPc by apreiml@fosstodon.org
2023-10-20T18:48:24Z
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@novenary @lanodan Exactly, the MitM certs where valid Let's Encrypt certs, that where present in the log. In this case I don't see how a client could detect the attack.
(DIR) Post #AayDp9YBclt73zUPBo by lanodan@queer.hacktivis.me
2023-10-20T18:55:26.083646Z
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@apreiml @novenary It wouldn't, that particular case is on the admin.But if no clients ever checks against CT, you risk having a blind spot where a CA simply doesn't adds malicious certificates into CT logs, rendering the whole thing pretty much useless.The OCSP part is because IIRC it also contains a part of the CT record, that said it's been a while since I've went into how the TLS protocol works.
(DIR) Post #AayEahdmhA12P2mVCS by lanodan@queer.hacktivis.me
2023-10-20T19:03:55.576967Z
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@novenary @apreiml Clients like browsers already do.And if they weren't: What else could appropriately check?Remember that MITM attacks based on partially re-routing people have long been a thing, specially from governments (most of which have their own CAs).
(DIR) Post #AayFQVUH7svJlh2GJc by lanodan@queer.hacktivis.me
2023-10-20T19:13:25.098977Z
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@novenary @apreiml Why the FUCK do I need to repeat myself at every other reply about this: The admin still needs to check the CT logs.It's *BOTH*, because if both aren't doing it, then you have a problem.