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Of which all that could have been averted by having another TLS public/private key issued but this time by the client side and it’s public key then given to the

Of which all that could have been averted by having another TLS public/private key issued but this time by the client side and it’s public key then given to the website , no? But who does that nowadays? I still do for my mutual TLS APIs. It’s only if the client public key (which is stored only in the web server could ALSO get hijack then all that would be … for naught (to the hacker’s gain, that is).

NovemberWhiskey 5y ago
Mutual TLS doesn't help here - the server TLS implementation can easily be configured to accept any certificate. Mutual TLS gives you mutual authentication, but if the server doesn't care whether the client is authentic or not (because it's been replaced by a malicious implementation) then how does that help?
- egberts1 5y ago
  .., if the server doesn’t , which is nearly all web browsers today. Not necessarily a properly configured Mutual-TLS non-browser API handler, but the article is talking about what most people use which is a web browser.
  - NovemberWhiskey 5y ago
    I don't really understand what you're describing here: which part of the following do you disagree with? TLS permits client (initiator of the session) and server (target of the session) to have certificates. The purpose of the client certificate is that the server may authenticate the client. The purpose of the server certificate is that the client may authenticate the server. Hence: mutual authentication. If the server is replaced by a malicious implementation that has the private key associated with a genuine certificate, the client will validate the server as authentic. This happens first in the TLS handshake. The malicious server will then happily receive the client certificate and accept it without any chain validation, because it doesn't really care whether the client is authentic or not. To repeat the point: the use of client certificates does not and cannot protect the client.
    - egberts1 5y ago
      If you own both the TLS endpoints, you can keep both keys and any attempt to intercept against the two different set of public keys will fail unless both and only both private keys are compromised. But that defense would only stand by requiring a prior imprint of TLS signatures at both endpoints which no web browser would be able to do during a mutual TLS unless that web browser also starts to takes not only the mutual-thingie client TLS cert but to remember the TLS server public key cert as well beforehanded; not a pretty easy thing to set up by an average web user if the web browser choose to support this. But you can do this strong protection of dual public key exchange for your own set of endpoints and no BGP hijack can get to it unless both-side’s private keys are compromised; it is just that web browser cannot bother with the prior fingerprinting of TLS server due to a variety of reasons (namely expiration, revocation, domain churn, …). This new big data collection of TLS server certa surely can only be rudimentary protection and certainly not against a timing attack, no? My assertion now is that it is the current design of the TLS handling by web browsers is purposely crippled for ease of use purposes. TLS protocol, however, remains robust against such a MitM at IP reroute-level if verification of TLS certs are done both ways and on BOTH sides; kinda like IPSec, right?
      - NovemberWhiskey 5y ago
        If you're requiring your client to expect a particular certificate, e.g. certificate pinning, then obviously you don't have this problem. You're also then not participating meaningfully in the internet PKI. You can just self-sign your root and be your own CA. You also don't need mTLS in that case - the two concepts are orthogonal. This is fine in a closed ecosystem, where you can also compel your trust roots into the clients and have a mechanism where you can push out updates to endpoint/public key mappings. This is why you still see HPKP for mobile apps. If DANE were actually a thing then it would also be an option for more open internet use cases; but the reality is that it too comes with its own security and operational problems, and essentially no TLS implementation support as a result of the chicken-and-egg problem. In any case, this is all outside of TLS, which only generally assumes PKIX.
        5y ago

NovemberWhiskey 5y ago

Mutual TLS doesn't help here - the server TLS implementation can easily be configured to accept any certificate. Mutual TLS gives you mutual authentication, but if the server doesn't care whether the client is authentic or not (because it's been replaced by a malicious implementation) then how does that help?

egberts1 5y ago
.., if the server doesn’t , which is nearly all web browsers today. Not necessarily a properly configured Mutual-TLS non-browser API handler, but the article is talking about what most people use which is a web browser.
- NovemberWhiskey 5y ago
  I don't really understand what you're describing here: which part of the following do you disagree with? TLS permits client (initiator of the session) and server (target of the session) to have certificates. The purpose of the client certificate is that the server may authenticate the client. The purpose of the server certificate is that the client may authenticate the server. Hence: mutual authentication. If the server is replaced by a malicious implementation that has the private key associated with a genuine certificate, the client will validate the server as authentic. This happens first in the TLS handshake. The malicious server will then happily receive the client certificate and accept it without any chain validation, because it doesn't really care whether the client is authentic or not. To repeat the point: the use of client certificates does not and cannot protect the client.
  - egberts1 5y ago
    If you own both the TLS endpoints, you can keep both keys and any attempt to intercept against the two different set of public keys will fail unless both and only both private keys are compromised. But that defense would only stand by requiring a prior imprint of TLS signatures at both endpoints which no web browser would be able to do during a mutual TLS unless that web browser also starts to takes not only the mutual-thingie client TLS cert but to remember the TLS server public key cert as well beforehanded; not a pretty easy thing to set up by an average web user if the web browser choose to support this. But you can do this strong protection of dual public key exchange for your own set of endpoints and no BGP hijack can get to it unless both-side’s private keys are compromised; it is just that web browser cannot bother with the prior fingerprinting of TLS server due to a variety of reasons (namely expiration, revocation, domain churn, …). This new big data collection of TLS server certa surely can only be rudimentary protection and certainly not against a timing attack, no? My assertion now is that it is the current design of the TLS handling by web browsers is purposely crippled for ease of use purposes. TLS protocol, however, remains robust against such a MitM at IP reroute-level if verification of TLS certs are done both ways and on BOTH sides; kinda like IPSec, right?
    - NovemberWhiskey 5y ago
      If you're requiring your client to expect a particular certificate, e.g. certificate pinning, then obviously you don't have this problem. You're also then not participating meaningfully in the internet PKI. You can just self-sign your root and be your own CA. You also don't need mTLS in that case - the two concepts are orthogonal. This is fine in a closed ecosystem, where you can also compel your trust roots into the clients and have a mechanism where you can push out updates to endpoint/public key mappings. This is why you still see HPKP for mobile apps. If DANE were actually a thing then it would also be an option for more open internet use cases; but the reality is that it too comes with its own security and operational problems, and essentially no TLS implementation support as a result of the chicken-and-egg problem. In any case, this is all outside of TLS, which only generally assumes PKIX.
      - 5y ago