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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. Joona Immonen‏ @rinorragi 6 Feb 2018
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      Replying to @troyhunt

      Joona Immonen Retweeted Tavis Ormandy

      About that 2FA. What is your opinion on SMS-2FA? @taviso was kind of harsh about it:https://twitter.com/taviso/status/942082082385182720 …

      Joona Immonen added,

      Tavis OrmandyVerified account @taviso
      Replying to @justinmberman @haroonmeer
      Even then, it's not that simple. For example, SMS-2FA is basically worthless. U2F on the other hand, while not a panacea, is fantastic if implemented correctly.
      3 replies 0 retweets 2 likes
    2. Troy Hunt‏Verified account @troyhunt 6 Feb 2018
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      Replying to @rinorragi @taviso

      It’s something in addition to a password alone so that’s good, the discussion then is how readily exploitable it is

      2 replies 0 retweets 3 likes
    3. Joona Immonen‏ @rinorragi 6 Feb 2018
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      Replying to @troyhunt @taviso

      I guess there is also a discussion about who you are trying to protect from and where do you live. Operators tend to be different around the globe. Also high profile players like you two might have different kind of concerns than regular users.

      1 reply 0 retweets 0 likes
    4. Joona Immonen‏ @rinorragi 6 Feb 2018
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      Replying to @rinorragi @troyhunt @taviso

      But back to original question. Would you invest on developing SMS-2FA and do you feel that it might give the user false sense of security?

      1 reply 0 retweets 0 likes
    5. Troy Hunt‏Verified account @troyhunt 6 Feb 2018
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      Replying to @rinorragi @taviso

      Yes, then no. SIM hijacking is very targeted and when you consider that in the context of common attacks like credential stuffing, it’s a big leap forward.

      3 replies 0 retweets 3 likes
    6. Tavis Ormandy‏Verified account @taviso 6 Feb 2018
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      Replying to @troyhunt @rinorragi

      The problem with SMS-2FA isn't "sim hijacking" - The issue is you're trying to solve the problem of an attacker who can steal passwords with a second password.

      2 replies 17 retweets 46 likes
    7. Seanie B.‏ @seanieb 6 Feb 2018
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      Replying to @taviso @troyhunt @rinorragi

      Which TOTP suffers from too. I still consider this and the "sim hijacking"* less important than the account life cycle issues @alexstamos highlights. Especially if you can just email support and convincingly claim you're locked out due to a new phone/lost @Yubico.

      3 replies 0 retweets 1 like
    8. Seanie B.‏ @seanieb 6 Feb 2018
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      Replying to @seanieb @taviso and

      * Where's the data on "sim hijacking"? I remember @riskybusiness covered a German SS7 attack, which had a bunch of caveats. Everything else seems to be targeted through social engineering cell phone providers, who have stepped up their security since.

      1 reply 0 retweets 0 likes
    9. 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
    10. 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
      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.

      6:43 AM - 6 Feb 2018
      • 7 Likes
      • 岡部 倫太郎 Allan Wirth Rick Deacon Ethics Gradient Ben Ryan Sleevi Jon Barber
      1 reply 0 retweets 7 likes
        1. New conversation
        2. 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
        3. 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
        4. 24 more replies

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