5 ms·

> Customers complaining that your SSL certificate is invalid Most customers will shrug their shoulders and try another site that doesn't throw a scary warning.

by wyday 18y ago

> Customers complaining that your SSL certificate is invalid Most customers will shrug their shoulders and try another site that doesn't throw a scary warning. Normal people don't report bugs. > customers complaining that you're a fraud You're right, this is a real problem. But blocking certificates outright isn't less of a problem.

tptacek 18y ago
I don't understand your logic. Revoking certificates will cause unpleasant SSL errors. Not revoking certificates will negate all the security of SSL. How could those two problems be comparable?
- wyday 18y ago
  > Revoking certificates will cause unpleasant SSL errors. Unpleasant errors scares away buyers. That is, Error + Credit Card = No Purchase > Not revoking certificates will negate all the security of SSL. Not true. The encryption part of the certificate is still there. However, the added assurance that you're really on the site you think is compromised. But has the assurance part of SSL certificates actually reduced phishing? Stupid people will still put all their money in BankOfShmamerica.com as long as it looks sort of like the BankOfAmerica.com site and doesn't throw any errors.
  - tptacek 18y ago
    If you think "the encryption part of the certificate" is still there, you don't really understand how SSL works. Without a secure certificate, you can't trust your SSL session keys. See: http://news.ycombinator.com/item?id=277284 http://news.ycombinator.com/item?id=277284
    - modoc 18y ago
      "the encryption part of the certificate" is still there as far as the wifi packets leaving your laptop are concerned, and as far as the poorly/maliciously configured linux router in the backroom of the coffee shop are concerned. So, is it 100% secure? No. Is there still a reasonably high barrier of entry to getting your CC number/bank login? Yes. That's like saying if you were using one of the weak Debian ssh keys, you might as well be using telnet. It's simply not true. The effort to steal your info is at least an order of magnitude (if not more) higher, even with weak ssh keys. The same situation applies here.
      - tptacek 18y ago
        You made the same point a few minutes ago, and I replied to it; long story short, you're not correct.
      - nailer 18y ago
        tptakec is 100% correct, but I like to explain stuff to people: The packets leaving your laptop are protected from being eavesdropped by third parties, but the party you're sending your banking password to is some asshole who now apparently runs a CA, and just issued a certificate telling your web browser he's your bank.
        modoc 18y ago
        The scenario under discussion (at least I as understood it from this particular thread of comments) is if we don't revoke all the compromisable certs. The scenario is NOT that I am connected to an attacker who has successfully used this attack against me. Under that scenario, then you've already lost your data (although I'd still hold it's better to have your CC stolen by one person, rather than two), so yes, that's bad. However, that's not the scenario that I've been discussing here. This thread came under the debate about the risks and issues with revoking all those certs immediately, versus not.
        tptacek 18y ago
        If you're saying, "we shouldn't do anything rash to mitigate an attack that requires Arjen Lenstra and a specially tuned cluster of PS3s to accomplish", then that makes sense. If you're saying, "we shouldn't do anything rash because certificates don't break encryption, only authentication", then you are perpetuating a really dangerous myth about SSL security.
    - wyday 18y ago
      You're right - I've never implemented SSL, and as such don't know the minutia of the algorithm. I didn't gather a lot of information from the link you posted, but this doc on the SSL handshake ( http://docs.sun.com/source/816-6156-10/contents.htm http://docs.sun.com/source/816-6156-10/contents.htm ) to my eyes doesn't show why you wouldn't be able to trust your session keys. Could you explain how session keys can be compromised?
      - stella 18y ago
        It doesn't make a difference whether the communication is encrypted if you can't verify with whom you are communicating.
        modoc 18y ago
        That's decidedly untrue. In this case I could be falling for a fake site and sending them my CC data, instead of Amazon, however I'm still protected from my CC being stolen by guy who setup the coffee house Wifi router.
        tptacek 18y ago
        Unfortunately, you too are misunderstanding how SSL works. If you own the coffee house WiFi router, you can decrypt any SSL session that traverses your network that doesn't use valid certificates. You simply need to inject your own certificate into the SSL session and fix a session key. You cannot secure a conversation between two unrelated parties over the Internet without some form of authentication, to "break the tie" if the attacker presents their own keys/certificates.
        modoc 18y ago
        Actually, I'm not. I have great respect for your security knowledge, but your consistent black & white views and your assumption that anyone who doesn't share them doesn't understand the technology is frustrating. If I own a coffee house router, or if I am simply sniffing un-encrypted wifi packets out of the air in the coffee house, logging traffic is extremely simple. I can log all traffic, or just traffic to http pages with names like login, or checkout, and I can do that very very very easily. It will log tons data automatically, and let me comb through it later. As a newbie to linux I could do that. The barrier preventing me from stealing the info you send over http is VERY low, and virtually anyone can do it. The attack you describe is much more difficult to execute. The number of people who could make that attack is several orders of magnitude smaller than the previous attack. Hence my risk is several orders of magnitude smaller. You're arguing that because skilled safe-crackers can open a safe, people should just leave their valuables on their lawn chairs out front. Security isn't black and white. Nothing will be 100% secure from every type of attack. It's a matter of raising the barrier of entry for an attack high enough that it's generally not worth the trouble.

by wyday 18y ago

tptacek 18y ago

I don't understand your logic. Revoking certificates will cause unpleasant SSL errors. Not revoking certificates will negate all the security of SSL. How could those two problems be comparable?

wyday 18y ago
> Revoking certificates will cause unpleasant SSL errors. Unpleasant errors scares away buyers. That is, Error + Credit Card = No Purchase > Not revoking certificates will negate all the security of SSL. Not true. The encryption part of the certificate is still there. However, the added assurance that you're really on the site you think is compromised. But has the assurance part of SSL certificates actually reduced phishing? Stupid people will still put all their money in BankOfShmamerica.com as long as it looks sort of like the BankOfAmerica.com site and doesn't throw any errors.
- tptacek 18y ago
  If you think "the encryption part of the certificate" is still there, you don't really understand how SSL works. Without a secure certificate, you can't trust your SSL session keys. See: http://news.ycombinator.com/item?id=277284 http://news.ycombinator.com/item?id=277284
  - modoc 18y ago
    "the encryption part of the certificate" is still there as far as the wifi packets leaving your laptop are concerned, and as far as the poorly/maliciously configured linux router in the backroom of the coffee shop are concerned. So, is it 100% secure? No. Is there still a reasonably high barrier of entry to getting your CC number/bank login? Yes. That's like saying if you were using one of the weak Debian ssh keys, you might as well be using telnet. It's simply not true. The effort to steal your info is at least an order of magnitude (if not more) higher, even with weak ssh keys. The same situation applies here.
    - tptacek 18y ago
      You made the same point a few minutes ago, and I replied to it; long story short, you're not correct.
    - nailer 18y ago
      tptakec is 100% correct, but I like to explain stuff to people: The packets leaving your laptop are protected from being eavesdropped by third parties, but the party you're sending your banking password to is some asshole who now apparently runs a CA, and just issued a certificate telling your web browser he's your bank.
      - modoc 18y ago
        The scenario under discussion (at least I as understood it from this particular thread of comments) is if we don't revoke all the compromisable certs. The scenario is NOT that I am connected to an attacker who has successfully used this attack against me. Under that scenario, then you've already lost your data (although I'd still hold it's better to have your CC stolen by one person, rather than two), so yes, that's bad. However, that's not the scenario that I've been discussing here. This thread came under the debate about the risks and issues with revoking all those certs immediately, versus not.
        tptacek 18y ago
        If you're saying, "we shouldn't do anything rash to mitigate an attack that requires Arjen Lenstra and a specially tuned cluster of PS3s to accomplish", then that makes sense. If you're saying, "we shouldn't do anything rash because certificates don't break encryption, only authentication", then you are perpetuating a really dangerous myth about SSL security.
  - wyday 18y ago
    You're right - I've never implemented SSL, and as such don't know the minutia of the algorithm. I didn't gather a lot of information from the link you posted, but this doc on the SSL handshake ( http://docs.sun.com/source/816-6156-10/contents.htm http://docs.sun.com/source/816-6156-10/contents.htm ) to my eyes doesn't show why you wouldn't be able to trust your session keys. Could you explain how session keys can be compromised?
    - stella 18y ago
      It doesn't make a difference whether the communication is encrypted if you can't verify with whom you are communicating.
      - modoc 18y ago
        That's decidedly untrue. In this case I could be falling for a fake site and sending them my CC data, instead of Amazon, however I'm still protected from my CC being stolen by guy who setup the coffee house Wifi router.
        tptacek 18y ago
        Unfortunately, you too are misunderstanding how SSL works. If you own the coffee house WiFi router, you can decrypt any SSL session that traverses your network that doesn't use valid certificates. You simply need to inject your own certificate into the SSL session and fix a session key. You cannot secure a conversation between two unrelated parties over the Internet without some form of authentication, to "break the tie" if the attacker presents their own keys/certificates.
        modoc 18y ago
        Actually, I'm not. I have great respect for your security knowledge, but your consistent black & white views and your assumption that anyone who doesn't share them doesn't understand the technology is frustrating. If I own a coffee house router, or if I am simply sniffing un-encrypted wifi packets out of the air in the coffee house, logging traffic is extremely simple. I can log all traffic, or just traffic to http pages with names like login, or checkout, and I can do that very very very easily. It will log tons data automatically, and let me comb through it later. As a newbie to linux I could do that. The barrier preventing me from stealing the info you send over http is VERY low, and virtually anyone can do it. The attack you describe is much more difficult to execute. The number of people who could make that attack is several orders of magnitude smaller than the previous attack. Hence my risk is several orders of magnitude smaller. You're arguing that because skilled safe-crackers can open a safe, people should just leave their valuables on their lawn chairs out front. Security isn't black and white. Nothing will be 100% secure from every type of attack. It's a matter of raising the barrier of entry for an attack high enough that it's generally not worth the trouble.