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Null-Prefix SSL Attacks Enabled In New sslsniff 48

Posted by timothy
from the ready-or-not-here-it-comes dept.
An anonymous reader writes "Moxie Marlinspike, who recently published new attacks on SSL at Defcon 17, seems to have released the new version of sslsniff which supports these attacks. While the release appears to coincide with a patch from Mozilla, every product that uses the Microsoft CryptoAPI is still vulnerable, including Internet Explorer and Outlook. The new version of sslsniff also supports built-in modes for hijacking software auto-updates that depend on SSL, and apparently includes techniques for defeating OCSP as well — making the elimination of existing null-prefix certificates difficult."
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Null-Prefix SSL Attacks Enabled In New sslsniff

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  • by sys.stdout.write (1551563) on Tuesday August 04, 2009 @09:10AM (#28940537)

    appears to coincide with a patch from Mozilla

    If some guy waited until Microsoft fixed a vulnerability to release a patch, but not before Mozilla fixed the patch, then we would all be crying foul.

    Since it's the other way around, nobody will have a problem I'm sure.

    • by sys.stdout.write (1551563) on Tuesday August 04, 2009 @09:11AM (#28940557)
      And by "fixed the patch" I mean "I'm retarded".

      English is hard.
    • by Kurusuki (1049294)
      If one waited until Microsoft fixed a vulnerability we'd be waiting until Hell is ordering winter parkas
    • Re: (Score:3, Informative)

      by The MAZZTer (911996)
      Microsoft issue a fix before Mozilla? I don't think you understand how "Patch Tuesday" works.
    • by BasharTeg (71923) on Tuesday August 04, 2009 @10:01AM (#28941271) Homepage

      You're absolutely right. If this guy didn't inform anyone except Mozilla, he's bringing browsers wars to a new low, by being willing to expose a majority of web users involved in e-commerce and other "secure" online access to his vulnerability for whatever the lead time of patching is, but exempting users of his favorite browser. IF that's what he did, that's ridiculous, childish, and petty.

      What about all the other vendors of SSL dependent software? SSL based VPNs like OpenVPN for example. No love for them either? Just Mozilla?

      It shows how people like Dan K are smart enough to recognize major vulnerabilities that can potentially affect massive amounts of service/traffic/commerce need to be handled differently. It doesn't reduce the respect you gain as a security researcher for finding such a major flaw to give vendors notification in a reasonable time period before publication. I'm all for full disclosure as a means of punishing companies that don't respond, but for larger vulnerabilities I think notification and a deadline are the way to go.

      • Re: (Score:1, Informative)

        by Anonymous Coward

        If this guy didn't inform anyone except Mozilla...

        From the security advisory at Mozilla [mozilla.org]

        Mozilla would like to thank Dan and the Microsoft Vulnerability Research team for coordinating a multiple-vendor response to this problem.

        Looks like MS was informed (as they certainly should have been), just considerably slower on the fix (imagine that?). How long should have Mozilla waited before releasing their fix? Until after Windows 7 ships and MS decides they can afford some dev cycles to go patch WinXP?

      • According to the article Dan K was one of the people who discovered the flaw. Why do you assume that Microsoft and others weren't notified months ago when Mozilla was?

      • by gnasher719 (869701) on Tuesday August 04, 2009 @10:41AM (#28942001)

        You're absolutely right. If this guy didn't inform anyone except Mozilla, he's bringing browsers wars to a new low, by being willing to expose a majority of web users involved in e-commerce and other "secure" online access to his vulnerability for whatever the lead time of patching is, but exempting users of his favorite browser. IF that's what he did, that's ridiculous, childish, and petty.

        Reading the article, there seemed to be a good reason to inform Mozilla first, because they were the most vulnerable. Apparently, to spoof say Internet Explorer, you need a certificate for "www.ebay.com\0.evilhackers.com", one for "www.amazon.com\0.evilhackers.com" and so on, but to spoof Mozilla-based browsers, a certificate for "*\0.evilhackers.com" will be accepted for _every_ site in existence.

        • by Benfea (1365845)
          I refuse to accept your answer! You are clearly part of the conspiracy against Microsoft! *chews on carpet*
      • OpenVPN wouldn't be affected by this. Unlike a browser, it doesn't go fetch a certificate and verify it against the domain name of the server; instead, the client already has the certificate and compares it to the server's certificate. In other words, OpenVPN's certificates aren't based on domain names. I'm pretty sure other SSL based VPNs are the same.
    • Re: (Score:3, Insightful)

      by John Hasler (414242)

      Evidently Mozilla was notified as early as February. What makes you think that Microsoft wasn't notified at the same time?

  • by Norsefire (1494323) * on Tuesday August 04, 2009 @09:11AM (#28940567) Journal
    Excellent technical skills, interest in hacking and a name that no security department will take seriously.
  • Gotta love that C null-terminated string brain damage!\0Heh. Stupid fsckers will never see this!!!

    • Gotta love that C null-terminated string brain damage!\0Heh. Stupid fsckers will never see this!!!

      Yay, Slashdot is written in perl. ;)

  • Protocols (Score:3, Interesting)

    by ledow (319597) on Tuesday August 04, 2009 @09:24AM (#28940745) Homepage

    Just wondering... will this help analysis of some "secured" protocols, maybe?

    I don't know how it works, but let's say something like Steam uses SSL or similar (I have no idea if it does, just pretend)... before we couldn't do the protocol analysis without a massive reverse-engineering going on (could only see "client to server" messages because we only have access to the client's private key). Now we might be able to fool non-patched SSL programs to believe that they are talking to an authentic server without having to delve into their code and thus be able to see / fake both sides of the conversation?

    Am I way off the mark, or is this now possible with unpatched programs relying on SSL etc. layers to hide their protocols?

    • by nxtw (866177)

      If the program uses a known API for encrypted communication and is linked dynamically, one could simply provide a shared library/DLL that copies the unencrypted messages... the API implementation used doesn't even have to be open source, as one could just write an intermediary library that implements all the functions of the original and copies the data before calling the original library.

      If the program dynamically links to an open-source library for encryption, or runs on Wine, you can just modify the impl

      • Yeah, right (Score:3, Interesting)

        by FranTaylor (164577)

        That is the first thing they think of. You can bet your lunch money that they statically link their crypto library, and then obfuscate the binary for good measure.

        • Re: (Score:2, Interesting)

          by greed (112493)

          Mua-ha-ha-ha.

          I've run into one of those annoying runtime licensing systems that not only uses out-of-the-box static build of OpenSSL in its code, it's an older version, too.

          Unobfuscated. With all the original OpenSSL symbol names. But they don't provide _all_ of OpenSSL, so you can't just use their old & busted one.

          Yes, this causes a serious multiple-definition problem if you want to use that library in an SSL application.

          Their "fix"? "Remove these filenames from the .a file we sent you. And these o

  • .. even extra unnecessary ones.

    Is an "atttack" anything like an "attack"?
  • The actual paper (Score:4, Informative)

    by Anonymous Coward on Tuesday August 04, 2009 @09:45AM (#28940999)

    Here's a link to the actual paper on the topic:
    http://www.thoughtcrime.org/papers/null-prefix-attacks.pdf

  • You gets no love.

    Tagged:noLoveForDanKaminsky

    ~Sticky

  • He found that if he created certificates for his own Internet domain that included null characters -- often represented with a \0 -- some programs would misinterpret the certificates.

    That's because some programs stop reading text when they see a null character.

    This is the same exploit used in an older Nintendo Wii jailbreak [marcansoft.com] - people just keep on using strcmp and its cousins to compare hashes.

  • I saw Moxie's talk at BlackHat. Extremely good presentation. There are three things necessary to carry out this attack:

    1. You need to convince a CA to sign your CR when you have a \0 in the common name.
    2. You need to target a browser or other application that uses a vulnerable certificate parser.
    3. You need to be able to execute a MitM attack.

    And of course, there's a weak "4":

    4. You need to be able to forge the OCRP "Try later" response, which is trivial since you're already "in the middle."

    As far as part #

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