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So DNSSEC is to ensure that returned IP address is not poisoned. And https is to verify the remote server.

My question is that when protected by https, under what circumstances, a client is vulnerable?

Say I go to https://www.facebook.com, even if I'm not protected by DNSSEC, what damage can an adversary cause? Let's assume no DigiNotar stuffs.

Thanks

7

Properly used https can mitigate the risk of not using DNSSsec because it is checked if the endpoint is the expected one by validating its certificate. Also, the data transport itself is protected. There are several things which can go wrong with https itself (weak ciphers, errors in validation process, too much trusted root CAs with same rights....) but if we assume that all this is handled properly (which is often not) https will give you the following protection:

  • You talk to the correct server.
  • The traffic between browser and server is protected in transit against sniffing and modification.

That's all you get.

Notably absent are protections against attacks caused by insecure web applications or bugs or design errors in the browser, that is CSRF, XSS, exploits using Flash, Java, Silverlight, ActiveX, include of 3rd-party code by the site you visit (i.e. social networks, tracking, advertisements...) and all the other typical attacks in today's web. And https will also not help if your computer is already compromised by malware or some security or helper software which does more harm than it helps.

  • Say I registered a domain name "faceboook.com", and I purchased an ssl certificate for my domain. If I'm able to compromise someone's DNS caches, i.e. hijacking their traffic to facebook.com to my server, will I be able to do MITM attacks? – Eniaczz Mar 12 '15 at 16:10
  • 1
    If you successfully claim ownership of somebody else domain by hijacking the registratrar or hijack mail server so that you get access to the mails, then you would be able to get a certificate signed by trusted CA with your key and then you could do a MITM attack using this certificate, unless the domain is explicitly pinned to a specific public key inside the browser (like the case with google.com and other major domains). – Steffen Ullrich Mar 12 '15 at 16:29
  • If there is a BGP hijacks (of the webserver IP OR the nameserver IPs) one could easily get a valid DV certificate he controls and hence enable full HTTPS without any warning to user (because valid CA), but still get all the traffic (you talk to the correct server, authentified by a certificate) and in that case HTTPS does not replace DNSSEC (which can be subverted too if the attacker can change the DS at parent). The Web PKI depends on the DNS, both at issuance time (CAs are starting to use DNSSEC validating resolvers at issuance time), and use time. – Patrick Mevzek Aug 1 at 14:52
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Let's assume no DigiNotar stuffs.

But that's where all of DNSSEC's benefits are! For example, here are two situations where no DNSSEC will result in a compromised session but using DNSSEC won't:

Hijacked resolver

  • A fraudulent certificate for a website is issued
  • An ISP's DNS servers are hijacked to point to the wrong IP

Cache poisoning

  • A fraudulent certificate for a website is issued
  • A resolver's cache is poisoned with a malicious IP

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