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

Tweets

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. Brian Campbell‏ @__b_c 19 Aug 2018
      • Report Tweet
      • Report NetzDG Violation
      Replying to @RichFelker

      a subdomain takeover on a site that uses a widely scoped cookie for an authenticated session, for example, which happened to Uber last year.

      1 reply 0 retweets 6 likes
    2. Brian Campbell‏ @__b_c 19 Aug 2018
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      Replying to @__b_c @RichFelker

      cases where multiple apps/servers are authorized with the same credential/token but aren't or shouldn't be trusted not to replay the token against other services

      1 reply 0 retweets 1 like
    3. Brian Campbell‏ @__b_c 19 Aug 2018
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      Replying to @__b_c @RichFelker

      coffee shop MITM

      1 reply 0 retweets 0 likes
    4. Rich Felker‏ @RichFelker 19 Aug 2018
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      Replying to @__b_c

      Coffee shop MITM is precluded by proper implementation of https by browser. Don't need another browser feature to deal with it.

      1 reply 0 retweets 5 likes
    5. Rich Felker‏ @RichFelker 19 Aug 2018
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      Replying to @RichFelker @__b_c

      Subdomain takeover is a real risk most developers and even many security reviewers aren't aware of, but if you are aware enough to try to mitigate you should properly scope cookies...

      1 reply 0 retweets 3 likes
    6. Rich Felker‏ @RichFelker 19 Aug 2018
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      Replying to @RichFelker @__b_c

      Sharing credentials is a 101-level fail...

      1 reply 0 retweets 1 like
    7. Rich Felker‏ @RichFelker 19 Aug 2018
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      Replying to @RichFelker @__b_c

      So subdomain takeover looks like the big one, and whether the tradeoffs of token binding are worth it seems to depend on how hard it is to fix poorly scoped cookies.

      1 reply 0 retweets 1 like
    8. Brian Campbell‏ @__b_c 19 Aug 2018
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      Replying to @RichFelker

      there are, of course, all kinds of protections available to prevent cookie theft. Token binding is unique in that it can prevent use after theft rather than trying to stop the theft itself. Both have value. Defence in depth etc. Token Binding also ...

      1 reply 0 retweets 0 likes
    9. Brian Campbell‏ @__b_c 19 Aug 2018
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      Replying to @__b_c @RichFelker

      ... can apply to things like OAuth and SSO tokens, which don't necessarily have the same characteristics as cookies. The browser case is maybe less compelling b/c of other cookie protections. But it's still useful IMHO. And, for better or worse, ...

      1 reply 0 retweets 2 likes
    10. Brian Campbell‏ @__b_c 19 Aug 2018
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      Replying to @__b_c @RichFelker

      adoption and deployment at large likely hinges on the browser supporting it

      1 reply 0 retweets 0 likes
      Tavis Ormandy‏Verified account @taviso 21 Aug 2018
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      Replying to @__b_c @RichFelker

      But you dodged Rich's main point, it has to be an attack that can't just be exploited using the same vector you used to get the cookie, right? Subdomain takeover is the first example I've heard that works, but that's pretty niche, you have to admit?

      5:10 PM - 21 Aug 2018
      • 2 Likes
      • mitchel lewis Rich Felker
      4 replies 0 retweets 2 likes
        1. New conversation
        2. Brian Campbell‏ @__b_c 22 Aug 2018
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          Replying to @taviso @RichFelker

          didn't mean to dodge so much as try to diplomatically say that I agree that there some limitations to the value prop around the browser/cookie protections but that there are other use cases, like SSO and native OAuth/API, that can benefit

          1 reply 0 retweets 1 like
        3. Brian Campbell‏ @__b_c 22 Aug 2018
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          Replying to @__b_c @taviso @RichFelker

          and that even when there are other attack vectors, I believe there's still value in enabling a cookie to be bound to a client generated asymmetric key because it does prevent the cookie from being used successfully in a different context without also getting the key

          1 reply 0 retweets 1 like
        4. 11 more replies
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        2. Rich Felker‏ @RichFelker 21 Aug 2018
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          Replying to @taviso @__b_c

          Rich Felker Retweeted hanno

          I think subdomain takeover is actually a much bigger threat than many ppl realize. IIRC @hanno has some nice work on this. Seehttps://twitter.com/hanno/status/1021350234117599234 …

          Rich Felker added,

          hanno @hanno
          Reported a subdomain takeover vuln to @Razer via their @Hacker0x01 program. After quite a while they now closed it as fixed. Except... http://pipe.mobileservices.razerzone.com/ 
          Show this thread
          2 replies 0 retweets 2 likes
        3. Tavis Ormandy‏Verified account @taviso 22 Aug 2018
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          Replying to @RichFelker @__b_c @hanno

          I asked Ryan about it, subdomain takeover has the same problem, you could just serve some js that does your attack instead of steal cookie then attack from your machine. I think this is another "why not just use the vector you used to get the cookie in the first place"?

          2 replies 0 retweets 2 likes
        4. 35 more replies
        1. New conversation
        2. Antonio Sanso‏Verified account @asanso 22 Aug 2018
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          Replying to @taviso @__b_c @RichFelker

          Agree on all the accounts. Said that subdomain takeover is less niche than imagine

          1 reply 0 retweets 0 likes
        3. Tavis Ormandy‏Verified account @taviso 22 Aug 2018
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          Replying to @asanso @__b_c @RichFelker

          I realized after this tweet that Token Binding doesn't solve subdomain takeover. The only example attack I've heard that does seem sound is accidental passive leak of cookies into logfiles.

          1 reply 0 retweets 3 likes
        4. 3 more replies
        1. mitchel lewis‏ @stautistic 23 Aug 2018
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          Replying to @taviso @__b_c @RichFelker

          A good argument can be made that Microsoft and their services need this feature more than the industry as a whole does. If you lack the capacity to account for these aforementioned scenarios without token binding, then compensating with token binding would make a lot of sense.

          0 replies 0 retweets 0 likes
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