3 ms·

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

by 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.

tptacek 18y ago
What you're not acknowledging, anywhere in the above 5 paragraphs of text, is that all the security you're talking about getting from SSL in this scenario is security that the attacker is choosing to give you. When we reason about information security, we don't usually give the attacker that kind of advantage. There is no such thing as a purely-passive attacker. In reality, no serious attacker is even going to bother sniffing your traffic; they're going to redirect it.
- modoc 18y ago
  Sorry, the scenario we're talking about here, as laid out by you: "Not revoking certificates will negate all the security of SSL." We're not talking about the scenario where a very smart attacker is targeting me with this security hole. We're talking about the impact of not revoking the certificates in question. At which point there is a very very small possibility that I will be targeted by an active attacker with the know-how to exploit this issue. The rest of the time SSL will continue to work as designed and will protect me from wifi snoopers and suspect routers. There absolutely are passive attackers. There are people running open wifi points that log http form submissions with a "password" field, and then try the same username/password on a few major sites (ebay, amazon, etrade, gmail, BoA, etc...) automatically (working on the assumption that people use the same login/password on the many non-ssl authed non-important sites as they do for their important accounts). Successful login data is marked. I have met people running these. It costs nothing, is fully automated, and has very little risk. They may not be "serious attackers", but the likelihood of one of them getting your mom's eTrade info is much higher than an active attacker targeting your mom.
  - tptacek 18y ago
    I'm sorry, I'm just not interested in talking about security in terms of attackers who are too dumb or lazy to carry out well-known, utterly practical attacks. You can keep saying that "the encryption part of SSL works fine with authentication"; if you add the phrase "as long as you're dealing with functionally retarded adversaries", I won't even call you on it.
    - modoc 18y ago
      Well known and utterly practical? You have been commenting about how difficult this attack is and how the MD5 collision breakthrough is still secret. You're not interested in the risk of or protection against provided by SSL encryption for a simple and probably relatively common passive attack? Because those people are lazy or dumb, we can write them off entirely and say SSL provides no security if there's a potential CA related exploit? I get that it's not as interesting a situation to think about, but I think that logically you can prove that SSL provides an increased security over http to the end user, even if some certs could be compromised. " (2) You have to be able to generate the collision within a short window of time to get the resulting product signed properly by the CA, so you need the new academic result (and the PS3s). (1) The attack is extremely difficult to pull off. (2) Critical details required to carry it out --- an academic breakthrough in MD5 collision-finding --- were actually withheld, meaning that no "zero-day" occurred. (3) The "fix" for this attack is for RapidSSL to randomize serials and stop using MD5, both of which will happen; if you believe certificates from before today are vulnerable, that's an even stronger argument for publishing. "
      - deleted 18y ago
        [deleted]
      - tptacek 18y ago
        The attack you are talking about it completely trivial. It relies on you being too dumb to even care if you have a real certificate. The attack Sotirov, et al have discovered is extremely hard. It works even if you check certificates.

by modoc 18y ago

tptacek 18y ago

What you're not acknowledging, anywhere in the above 5 paragraphs of text, is that all the security you're talking about getting from SSL in this scenario is security that the attacker is choosing to give you. When we reason about information security, we don't usually give the attacker that kind of advantage. There is no such thing as a purely-passive attacker. In reality, no serious attacker is even going to bother sniffing your traffic; they're going to redirect it.

modoc 18y ago
Sorry, the scenario we're talking about here, as laid out by you: "Not revoking certificates will negate all the security of SSL." We're not talking about the scenario where a very smart attacker is targeting me with this security hole. We're talking about the impact of not revoking the certificates in question. At which point there is a very very small possibility that I will be targeted by an active attacker with the know-how to exploit this issue. The rest of the time SSL will continue to work as designed and will protect me from wifi snoopers and suspect routers. There absolutely are passive attackers. There are people running open wifi points that log http form submissions with a "password" field, and then try the same username/password on a few major sites (ebay, amazon, etrade, gmail, BoA, etc...) automatically (working on the assumption that people use the same login/password on the many non-ssl authed non-important sites as they do for their important accounts). Successful login data is marked. I have met people running these. It costs nothing, is fully automated, and has very little risk. They may not be "serious attackers", but the likelihood of one of them getting your mom's eTrade info is much higher than an active attacker targeting your mom.
- tptacek 18y ago
  I'm sorry, I'm just not interested in talking about security in terms of attackers who are too dumb or lazy to carry out well-known, utterly practical attacks. You can keep saying that "the encryption part of SSL works fine with authentication"; if you add the phrase "as long as you're dealing with functionally retarded adversaries", I won't even call you on it.
  - modoc 18y ago
    Well known and utterly practical? You have been commenting about how difficult this attack is and how the MD5 collision breakthrough is still secret. You're not interested in the risk of or protection against provided by SSL encryption for a simple and probably relatively common passive attack? Because those people are lazy or dumb, we can write them off entirely and say SSL provides no security if there's a potential CA related exploit? I get that it's not as interesting a situation to think about, but I think that logically you can prove that SSL provides an increased security over http to the end user, even if some certs could be compromised. " (2) You have to be able to generate the collision within a short window of time to get the resulting product signed properly by the CA, so you need the new academic result (and the PS3s). (1) The attack is extremely difficult to pull off. (2) Critical details required to carry it out --- an academic breakthrough in MD5 collision-finding --- were actually withheld, meaning that no "zero-day" occurred. (3) The "fix" for this attack is for RapidSSL to randomize serials and stop using MD5, both of which will happen; if you believe certificates from before today are vulnerable, that's an even stronger argument for publishing. "
    - deleted 18y ago
      [deleted]
    - tptacek 18y ago
      The attack you are talking about it completely trivial. It relies on you being too dumb to even care if you have a real certificate. The attack Sotirov, et al have discovered is extremely hard. It works even if you check certificates.