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taviso's profile
Tavis Ormandy
Tavis Ormandy
Tavis Ormandy
Verified account
@taviso

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Tavis OrmandyVerified account

@taviso

Vulnerability researcher at Google. This is a personal stream, opinions expressed are mine.

California
taviso.decsystem.org
Joined April 2008

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    1. Tavis Ormandy‏Verified account @taviso 6 Feb 2018
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      Replying to @seanieb @troyhunt and

      People don't claim that SMS-2FA is perfect, they claim it's "an improvement". If the issue was SMS hijacking, then that would require a new capability from the attacker. In fact, it can just be phished, and therefore does not require any new capability from attackers.

      2 replies 2 retweets 6 likes
    2. Seanie B.‏ @seanieb 6 Feb 2018
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      Replying to @taviso @troyhunt and

      They could Phish it, but it's much harder for phishers to build the infra to do so before the code expires. Eg. Real time password entry and proxying the response, and then storing the session cookie. Fwiw I agree, but we need to work harder to reduce the u2f life cycle issues

      1 reply 0 retweets 0 likes
    3. Tavis Ormandy‏Verified account @taviso 6 Feb 2018
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      Replying to @seanieb @troyhunt and

      It requires a few new lines of php, yes. I don't agree that qualifies as "much harder" 🙂 I think the bare minimum requirement for "raising the bar" is a new capability the attacker hasn't already demonstrated.

      1 reply 0 retweets 7 likes
    4. Seanie B.‏ @seanieb 6 Feb 2018
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      Replying to @taviso @troyhunt and

      I think it's much harder to deploy that to a large number of vulnerable WordPress and Joomla sites. And I'm not seeing it in the wild, but that's probably because no one uses 2fa 🤷‍♂️ (I worry my replies come off as disagreement rather than nuanced agreement)

      1 reply 0 retweets 0 likes
    5. Tavis Ormandy‏Verified account @taviso 6 Feb 2018
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      Replying to @seanieb @troyhunt and

      I don't think it's harder, but you're right - we don't see it for opportunistic phishing yet because why bother investing in supporting it to increase victim yield by 1%? It's just bad economics.

      1 reply 0 retweets 4 likes
    6. Tavis Ormandy‏Verified account @taviso 6 Feb 2018
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      Replying to @taviso @seanieb and

      The key point is that phishers aren't going to pack up and go home because they now have to phish two passwords instead of one, they'll just take the hit and rewrite their scripts when it makes economic sense to do so 🙂

      2 replies 2 retweets 10 likes
    7. Seanie B.‏ @seanieb 6 Feb 2018
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      Replying to @taviso @troyhunt and

      Agreed. My bet is that in the interim I can protect more users using SMS. Then transitioning them to push (ala Google approach) and U2f when we can.

      1 reply 0 retweets 2 likes
    8. M Schommer  🇪🇺‏ @musevg 6 Feb 2018
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      Replying to @seanieb @taviso and

      IMHO the issue with SMS 2FA isn't with the GSM attacks by https://de.m.wikipedia.org/wiki/Karsten_Nohl … but with rogue apps intercepting SMSes on smart phones. But either way, NIST 800-63B has deprecated SMS for 2FA, so it's basically dead. Or at least walking dead ;)

      1 reply 0 retweets 0 likes
    9. Tavis Ormandy‏Verified account @taviso 6 Feb 2018
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      Replying to @musevg @seanieb and

      Even U2F is useless on a compromised endpoint. If you require a solution for phishing to work on a compromised endpoint, then I wouldn't hold your breath waiting 🙂.

      1 reply 0 retweets 4 likes
    10. Alex Stamos‏Verified account @alexstamos 6 Feb 2018
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      Replying to @taviso @musevg and

      The primary scenario that SMS 2FA prevents is account takeover via password reuse, not live phishing. Our data shows that the former is many many times more prevalent.

      2 replies 3 retweets 24 likes
      Tavis Ormandy‏Verified account @taviso 6 Feb 2018
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      Replying to @alexstamos @musevg and

      I'm not sure what I said that you're disagreeing with! It seems completely plausible to me that dumped creds are tested more often than phishing, I don't think I've disputed that?

      12:43 PM - 6 Feb 2018
      1 reply 0 retweets 0 likes
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        2. Alex Stamos‏Verified account @alexstamos 6 Feb 2018
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          Replying to @taviso @musevg and

          I'm disagreeing with SMS 2FA being "basically useless". I don't think the data supports that.

          5 replies 0 retweets 13 likes
        3. zeynep tufekci‏Verified account @zeynep 10 Feb 2018
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          Replying to @alexstamos @taviso and

          Don't have big, systematic data on this but I constantly hear all over the world from people without any 2FA whose accounts get taken over via password reuse and much rarer live phishing of SMS 2FA. I do push people to U2F but, ceteris paribus, SMS 2FA seems way better than none.

          1 reply 1 retweet 7 likes
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