3 ms·

DNSSEC does not protect at all against the attack described in the article.

• egberts1 5y ago
  No, but endpoint to endpoint DNSSEC server/client with no recursion enabled should have your host’s DNS caching do the hard authoritative lookups and should alert you of such BGP hijack and if configured for DNSSEC-only presumably prevents you from going through your crypto-based transaction in that scenario. Of course, TLS, HTTPS, JavaScript and TCP attack vectors are another whole ball of wax.
  • detaro 5y ago
    No, it wouldn't alert you. The DNS response isn't tampered with and is still legitimate.
    • egberts1 5y ago
      So what you are (and the article is) saying is that this BGP hijack is more about inserting a MitM transparent TLS thus leaving both endpoints intact? This is why we can’t have nice things (such as TLS Client Side (or mutual TLS) easily enforced).
      • NovemberWhiskey 5y ago
        No - the point is that if your CA allows an HTTP-01 challenge for certificate issuance, then anyone who can hijack the IP addresses (to which your DNS points) with a BGP attack can subvert that CA to issue their own TLS certificates and subsequently impersonate your service.
        • egberts1 5y ago
          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gives you mutual authentication, but if the server doesn't care whether the client is authentic or not (because it's been replaced by a malicious implementation) then how does that help?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?
        • nilsbunger 5y ago
          Isn’t it sufficient if any CA allows the HTTP-01 challenge for your domain?
          • detaro 5y ago
            Depends if you've locked in a CA with a CAA record or not. If not, then yes, any CA that can be fooled is enough.
            • mittalprat 5y ago
              Having a CAA record and pointing to a CA like Let's Encrypt that uses domain validation from multiple vantage points on the Internet is a useful idea and raises the bar for an adversary. I should point out that BGP attacks can also target the CAA records themselves since the DNS ecosystem is itself insecure. This is why such attacks are not easy to defend against, and require holistic improvements across internet routing, PKI, and web security practices.....
              • egberts1 5y ago
                It is only because the web browsers are still not doing DNSSEC-only query and validation, CAA can easily be spoofed right there. To avert a DNSSEC-secured DNS CAA record from being tampered under BGP hijack, both endpoints must deploy their own cacheless DNSSEC authoritative-only resolvers before commencing mTLS endpoint communication. (Like a web browser would even do that /s). This places the trust of DNSSEC to right at the 13 DNS Root Servers whose private key are stored in a HSM key vault. So, hijacking a DNS infrastructure to tamper the CAA record is only possible because 1) web browser don’t bother with DNSSEC 2) domain owner don’t bother with DNSSEC protection. But even with insecure DNS, I assert that a properly designed REST/HTTPS/“mTLS” API (but would then be totally unusable by web browsers) would still not be intercepted under BGP hijack scenario so that is still an option for any B2B scenario.
    • NovemberWhiskey 5y ago
      Right. There were no DNS changes at all and none were needed to execute the attack. It was IP (at the routing layer) that was subverted; i.e. the IP addresses resolved from DNS remained the same but the traffic to them was redirected.
      • egberts1 5y ago
        I now get that the DNS no-change part. Was focused on the latter distinctions between: - incomplete mTLS and lack of DNSSEC implementation (found in all web browsers) - proper two-way mTLS with PKI validation of CA chain whose DNS CAA record is verified as properly protected by DNSSEC. The latter distinction gets your data through a BGP hijack safely from any MitM; former one, not so much.